ASTM F3324-19(2023)

Standard Test Method for Measurement of Cut Resistance to Chainsaw in Leg Protective Devices

SIGNIFICANCE AND USE
5.1 The purpose of this test method is to provide a measurable criterion of performance about the level of cut resistance provided by different types of protective garments and protective coverings worn by chainsaw operators.  
5.2 This test method is intended to show to what level a protective garment can offer resistance to the cutting action of a chainsaw.  
5.3 The protection that can be demonstrated by the garments and coverings tested in accordance with this test method is achieved by: (1) the cut resistance of the material to cutting when put in contact with saw chain; (2) pulling a part of the material or yarns in the material so that they are drawn into the chain and drive mechanism to block the chain movement; (3) the fibers of the materials used to demonstrate both high resistance to cutting and the capacity to absorb rotational energy, so that chain speed can be slowed down sufficiently to stop the movement of the saw chain; or (4) any combination of these.  
5.4 This test method does not purport to evaluate comfort of lower body protective garments.  
5.5 In case of a dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, the purchaser and the supplier should perform comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens from the same lot of components to be evaluated. The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. If a bias is found, either its cause must be determined and corrected or the purchaser and the supplier must agree to interpret future test results in light of the known bias.
SCOPE
1.1 This test method2 measures cut resistance of garments and devices worn to protect the lower body (legs) when operating a chainsaw.  
1.2 This test method may be used to test for compliance to minimum performance requirements in established safety standards.  
1.3 The values stated in SI units are to be regarded as standard.
Note 1: The values stated in each system may not be exact equivalents; therefore, each system must be used independently of the other, without combining values in any way.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 13.340.50 - Leg and foot protection
• Technical Committee: F23 - Personal Protective Clothing and Equipment
• Drafting Committee: F23.20 - Physical

Relations

• Replaces: ASTM F3324-19 - Standard Test Method for Measurement of Cut Resistance to Chainsaw in Leg-Protective Devices
• Effective Date: 01-Nov-2023

Overview

ASTM F3324-19(2023): Standard Test Method for Measurement of Cut Resistance to Chainsaw in Leg Protective Devices defines a laboratory procedure for evaluating the cut resistance of garments and protective devices designed to protect the lower body (legs) of chainsaw operators. Published by ASTM International, this test method ensures that chainsaw protective clothing and coverings meet minimum performance requirements, providing quantifiable data on their ability to resist or mitigate chainsaw-related injuries.

The procedure measures how different materials, fabrics, and composite assemblies respond when impacted by a running chainsaw under controlled conditions. It does not address other aspects such as comfort or ergonomic design, focusing exclusively on cut resistance performance.

Key Topics

• Cut Resistance Evaluation: The standard details how tested garments resist cutting, slow chain speed (energy absorption), or clog/stop the saw (jamming and chain stop).
• Chainsaw Testing Parameters: Specifies apparatus, sample mounting, chainsaw operational setup, and data acquisition methods for accurate and repeatable results.
• Pass/Fail Criteria: Establishes the threshold stopping speed and defines conditions for success (effective protection) or failure (cut-through, excessive penetration, or short stop time).
• Sampling and Precision: Outlines procedures for sampling, specimen preparation, and requirements for interlaboratory consistency, including recommendations for resolving differences in results.
• Safety and Compliance: Reiterates the responsibility of users to implement appropriate safety, health, and environmental precautions when employing this standard.
• International Standards Alignment: Developed in accordance with WTO principles for global applicability and harmonization in the field of personal protective equipment (PPE).

Applications

ASTM F3324-19(2023) is widely used by:

• Manufacturers of chainsaw-protective clothing seeking to validate or certify their products’ compliance with industry safety benchmarks.
• Safety organizations and regulatory bodies establishing minimum performance standards for leg protection in forestry, arboriculture, landscaping, and emergency response.
• Testing laboratories conducting comparative analyses of fabric and garment performance across different brands or product batches.
• Procurement and quality managers, ensuring product consistency, verifying supplier compliance, and resolving performance disputes for commercial shipments.
• Researchers and product developers focused on advancing material science for enhanced personal protective equipment.

Typical products assessed using this standard include protective chaps, pants, and gaiters for chainsaw users. Meeting or exceeding ASTM F3324-19(2023) requirements supports claims of effective “chainsaw cut resistance” in PPE product portfolios.

Related Standards

• ASTM D123 – Terminology Relating to Textiles
• ASTM D1056 – Specification for Flexible Cellular Materials - Sponge or Expanded Rubber
• ASTM D1776/D1776M – Practice for Conditioning and Testing Textiles
• ASTM F1494 – Terminology Relating to Protective Clothing
• MIL-STD-105 – Sampling Procedures and Tables for Inspection by Attributes
• FS 5100-86 – Type II Cloth, Duck, Nylon, Polyurethane Coated

Other international standards for chainsaw protective clothing, such as those set by ISO or European Norms (EN), may reference ASTM F3324 methodology or use similar testing concepts to demonstrate compliance with global PPE regulations.

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Keywords: ASTM F3324-19(2023), chainsaw cut resistance, protective clothing standard, leg protective devices, PPE, chainsaw safety gear, testing method, personal protective equipment, forestry safety, chainsaw operator safety

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3324 − 19 (Reapproved 2023)
Standard Test Method for
Measurement of Cut Resistance to Chainsaw in Leg
Protective Devices
This standard is issued under the fixed designation F3324; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope F1494 Terminology Relating to Protective Clothing
2.2 Military Standard:
1.1 This test method measures cut resistance of garments
MIL-STD-105 Sampling Procedures and Tables for Inspec-
and devices worn to protect the lower body (legs) when
tion by Attributes
operating a chainsaw.
2.3 Federal Standard:
1.2 This test method may be used to test for compliance to
FS 5100-86 Type II, Cloth, Duck, Nylon, Polyurethane
minimum performance requirements in established safety stan-
Coated
dards.
1.3 The values stated in SI units are to be regarded as
3. Terminology
standard.
3.1 Definitions:
NOTE 1—The values stated in each system may not be exact equiva-
3.1.1 chainsaw, n—a portable, power-operated tool used for
lents; therefore, each system must be used independently of the other,
cutting wood that has cutters linked in a chain.
without combining values in any way.
3.1.2 chain speed, n—the speed of synchronized movement
1.4 This standard does not purport to address all of the
of linked cutters around a guide bar and sprocket.
safety concerns, if any, associated with its use. It is the
3.1.3 chain stop, n—the resulting action when a material
responsibility of the user of this standard to establish appro-
clogs (jams) the drive sprocket or slows the speed sufficiently
priate safety, health, and environmental practices and deter-
to prevent advancement of the saw chain.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor- 3.1.4 cut resistance, n—in chainsaw testing, the ability of a
material, while in contact with the linked cutters, to resist
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the cut-through of the cutters of a moving saw chain independent
Development of International Standards, Guides and Recom- of either jamming or chain stop.
mendations issued by the World Trade Organization Technical
3.1.5 cut-through, n—for chainsaw cut resistance, the action
Barriers to Trade (TBT) Committee.
of a running chainsaw after complete breakthrough of either a
protective garment or protective device.
2. Referenced Documents
3.1.5.1 Discussion—When a cut-through (0.64 cm) is
2.1 ASTM Standards:
effected, speed of the saw chain must be measured.
D123 Terminology Relating to Textiles
3.1.6 jamming, n—for chainsaw cut resistance, the clogging
D1056 Specification for Flexible Cellular Materials—
action manifested by a protective garment or a device that can
Sponge or Expanded Rubber
produce a chain stop.
D1776/D1776M Practice for Conditioning and Testing Tex-
3.1.7 lower body, n—that part of the human body which
tiles
includes all portions between the waist and feet, not to include
1 the feet.
This test method is under the jurisdiction of ASTM Committee F23 on Personal
Protective Clothing and Equipment and is the direct responsibility of Subcommittee
3.1.8 protective clothing, n—an item of clothing that is
F23.20 on Physical.
specifically designed and constructed for the intended purpose
Current edition approved Nov. 1, 2023. Published November 2023. Originally
of isolating all or part of the body from a potential hazard, or
approved in 2018. Last previous edition approved in 2019 as F3324 – 19. DOI:
10.1520/F3324-19R23.
isolating the external environment from contamination by the
This standard was developed as a replacement for the archived CAN/BNQ
clothing.
1923-450.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,
the ASTM website. Philadelphia, PA 19111-5094, http://quicksearch.dla.mil.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3324 − 19 (2023)
3.1.8.1 Discussion—For chainsaw cut-resistant protective resistance to cutting and the capacity to absorb rotational
clothing, the potential hazard is exposure to a running power energy, so that chain speed can be slowed down sufficiently to
saw chain. stop the movement of the saw chain; or (4) any combination of
these.
3.1.9 saw chain, n—a closed loop of cutters linked together
for use in a portable, power-operated tool.
5.4 This test method does not purport to evaluate comfort of
lower body protective garments.
3.1.10 threshold stopping speed, n—chain speed that results
in a ⁄4 in. cut in the bottom layer of the protective pad liner in
5.5 In case of a dispute arising from differences in reported
a chainsaw leg protective device.
test results when using this test method for acceptance testing
3.1.10.1 Discussion—This value establishes the relationship
of commercial shipments, the purchaser and the supplier
between the probability of cutting through the protective
should perform comparative tests to determine if there is a
clothing (or foot protective device) and the speed of the saw
statistical bias between their laboratories. Competent statistical
chain. For lower chain speeds, the probability of cut-through
assistance is recommended for the investigation of bias. As a
approaches zero, while for higher chain speeds, the probability
minimum, the two parties should take a group of test speci-
of cut-through approaches one.
mens from the same lot of components to be evaluated. The test
specimens should then be randomly assigned in equal numbers
3.2 For definitions of other textile terms used in this test
to each laboratory for testing. If a bias is found, either its cause
method, refer to Terminology D123.
must be determined and corrected or the purchaser and the
3.3 For definitions of other protective clothing terms used in
supplier must agree to interpret future test results in light of the
this test method, refer to Terminology F1494.
known bias.
3.4 Pass/fail is a threshold stopping speed value measured in
meters per second (feet per minute) of chain travel speed that
6. Apparatus
results in the stated 6 mm ( ⁄4 in.) cut in the bottom of the lining
6.1 Apparatus consists of three main components:
of the performance pad of a chainsaw protective device. (See
6.2 Specimen Holder:
3.1.10.)
6.2.1 A stationary wooden cylinder having a diameter of
4. Summary of Test Method
152 mm (6 in.) and a minimum length of 356 mm (14 in.) (see
Figs. 1 and 2).
4.1 Test specimens are securely mounted on a test apparatus
6.2.1.1 The cylinder is covered with a vinyl nitrile foam
that simulates a human leg.
having a thickness of 18 mm (0.71 in.) (see Figs. 1 and 2). This
4.2 A chainsaw of specific characteristic and operating at a 2
covering shall have a density between 55 and 80 kg ⁄m and its
designated speed is brought into contact with the test specimen.
resistance to a 25 % compression shall be between 10 and
4.2.1 The cutting action of the saw chain will achieve one of
20 kPa, measured in accordance with the testing procedure in
the following results: (1) complete cut-through with chain stop,
Specification D1056.
(2) complete cut-through without chain stop, (3) no cut-
NOTE 3—Ensolite M, a synthetic foam rubber made of PVC and NBR,
through with a chain stop, or (4) no cut-through without a chain
meets the requirements stipulated in Specification D1056.
stop.
6.2.1.2 Two specimen attachment plates, each secured by
4.3 Chain speed is measured electronically just prior to
two screws to the wooden cylinder parallel to the axis of that
contact with test specimen. Chain speed is adjusted and
cylinder. Each plate is 75 by 25 mm (3 by 1 in.) (see Figs. 1
reported based on these measurements.
and 2).
NOTE 2—Materials may be characterized by repeated testing at different
6.2.1.3 The stationary wooden cylinder shall be attached to
speeds; for quality control, results may be reported as “pass” or “fail” at
a swivel mechanism that allows the mandrel to be moved to an
one pre-selected chain speed.
angle of either 45° or 90° to the vertical plane of the guide bar.
5. Significance and Use Specimen must be securely attached to mandrel to prevent
movement of specimen.
5.1 The purpose of this test method is to provide a measur-
6,7
able criterion of performance about the level of cut resistance 6.3 Chainsaw and Related Equipment:
provided by different types of protective garments and protec- 6.3.1 Saw:
tive coverings worn by chainsaw operators.
6.3.1.1 A gas-powered chainsaw, having an idle speed of
2250 6 250 rpm and a maximum power of 3.3 6 0.3 kW at
5.2 This test method is intended to show to what level a
8500 rpm that meets the following specifications: (1) minimum
protective garment can offer resistance to the cutting action of
3 3
66.7 cm or 4.0 in. ; (2) bore 50 mm; (3) stroke 34 mm; (4)
a chainsaw.
5.3 The protection that can be demonstrated by the garments
and coverings tested in accordance with this test method is 5
See Appendix X1 to review maintenance checklist.
achieved by: (1) the cut resistance of the material to cutting
Husqvarna Model 570 XP with an eight-tooth drive sprocket, available from
Husqvarna, http://www.husqvarna.com.
when put in contact with saw chain; (2) pulling a part of the
This is the sole source of supply known to the committee at this time. If you are
material or yarns in the material so that they are drawn into the
aware of alternative suppliers, please provide this information to ASTM Headquar-
chain and drive mechanism to block the chain movement; (3)
ters. Your comments will receive careful consideration at a meeting of the
the fibers of the materials used to demonstrate both high responsible technical committee, which you may attend.
F3324 − 19 (2023)
FIG. 3 Post Contact with Specimen (Front View) and Data
Item Quantity Description
Acquisition System
A 1 steel plate 0.25 by 576 by 670 mm
B 2 steel plate 0.25 by 216 by 375 mm
C 2 steel plate 0.25 by 208 by 216 mm
D 1 steel tube 0.75 by ID – 1 mm OD by 172 mm
E 1 aluminum plate 0.5 by 4 by 14.5 mm
F 1 hardwood or white pine 152 by 400 mm
G 2 hinge 3 by 3 by ⁄16 in.
H 1 foam pad 15 by 180 by 360 mm + glue
I 6 threaded rod 0.40 by 16 by 120 mm
J 12 bolt 0.40 by 16 mm
K 8 wood screw 8 by 0.75 mm TR
L 1 steel axle 0.75 mm diameter × 350 threaded
0.75 mm × 10 mm × 80 mm at each end
M 2 pillow block VPS112 valuline browing
N 5 bolt 0.75 by 10 mm
O 1 hex bolt 0.75 by 10 by 70 mm
P 1 square 30 mm × 90 mm × ⁄16 × 75L
Q 1 stopping block 20 mm × 40 mm × 60L
R 1 lever support ⁄16 × 80 mm × 130 mm
S 1 lever 0.25 by 60 by 120 mm
T 1 axle 0.250
U 1 compression spring
V 1 micro-switch
FIG. 4 Post Contact with Specimen (Rear View)
W 1 safety shield pivoting on D
NOTE 1—Measurements are in millimetres. Arcs of a circle are
measured on the circumference of the wood cylinder.
clutch engagement speed of 3450 6 250 rpm; (5) maximum
FIG. 1 Specimen Holder (Front View Facing Chainsaw)
no-load speed of 12 500 rpm; (6) maximum no-load chain
speed of 27 m ⁄s (5475 fpm); and (7) eight-tooth rim drive
sprocket. (See Figs. 3 and 4.)
6.3.1.2 Throttle control mechanism is used to maintain
constant saw chain speed.
6.3.1.3 The engine of the chainsaw is a two-stroke engine
that uses a gasoline/oil mixture. The gasoline shall be premium
unleaded without alcohol additive and having a minimum
anti-knock rating of 90. The oil shall be a high-quality,
two-stroke oil specially developed for chainsaws. Mix ratio is
50 + 1 (2 % two-stroke oil to 98 % gasoline).
6.3.1.4 The chainsaw shall be fitted with a resistive-type
plug to reduce interference with the chain speed electronics.
NOTE 4—When testing constraints prevent dynamometer verification,
the technician is responsible for checking that the engine is running
smoothly, starts readily, has a clean screen, if present, a good spark plug,
and so forth.
FIG. 2 Specimen Holder (Attachment and Positioning) NOTE 5—All requirements of the chainsaw are determined in accor-
dance with many manufacturers’ published specifications.
F3324 − 19 (2023)
8,7
6.3.2 Chain: 7. Hazards
6.3.2.1 A chain with a pitch of 10 mm ( ⁄8 in.), a 0.058 in.
7.1 Warning—The chainsaw equipment used in this test
gage, and a round ground full chisel cutter.
method can pose a potential danger to the technician if specific
6.3.2.2 New chain may be used without sharpening, or the
safety cautions are not followed.
chain must be sharpened using the sharpening procedure noted
7.2 As a minimum safety precaution, it is suggested that the
in Annex A1 before testing.
spark plug wire be disengaged until the engine needs to be
6.3.3 Guide Bar:
started.
6.3.3.1 A guide bar having a length of 500 mm (20 in.), with
an eleven-tooth roller-nose sprocket, designed to accommodate
7.3 As a further safety precaution, it is suggested that the
a 10 mm ( ⁄8 in.) pitch, 0.058 in. gage saw chain.
spark plug wire be grounded by circuitry after cutting the lower
6.3.3.2 The roller nose on the guide bar will need to be
wire of the data collection system. If the chain stops before this
cleaned at periodic intervals. To facilitate repeated cleanings,
wire is cut or if the chain slides over the specimen, a timer
the rivets attaching the roller nose to the bar should be
should limit the test and stop the engine by grounding the
replaced. Modification requires that rivets be removed and
electric circuitry of the chainsaw.
holes be enlarged by drilling, so that aircraft-quality bolts and
7.4 The technician performing this test method should use
locking nuts can be used.
ear protection to avoid potential hearing injury.
6.3.4 Chain Guidance and Lubrication:
6.3.4.1 The saw chain shall be able to turn freely around the 7.5 The technician performing this test method should use
drive sprocket and roller nose. The system shall be adequately eye protection to avoid potential eye injury.
lubricated. Chain tension shall be adjustable so that application
7.6 The chainsaw motor should be vented to prevent poten-
of a force of 15 N on the middle of the guide bar causes a chain
tial danger posed by carbon monoxide gas.
deflection of 6 6 0.5 mm.
6.4 Chainsaw Support Bracket:
8. Sampling
6.4.1 The saw is attached to a metal plate that rotates freely
8.1 Lot Sample—As a lot sample for acceptance testing, take
around the axle (see Figs. 5-7).
at random the number of shipping containers directed in an
6.4.2 The horizontal distance between the pivot of the saw
applicable material specification or other agreement between
and the central axis of the specimen support is 365 6 1 mm
the purchaser and the supplier. Consider shipping containers to
(14.2 6 0.125 in.) (see Figs. 5 and 6).
be the primary sampling units.
6.4.2.1 The vertical distance between the pivot of the saw
and the center of the drive sprocket cannot exceed 127 mm NOTE 6—An adequate specification or other agreement between the
purchaser and the supplier requires taking into account the variability
(5 in.).
between shipping containers, between laboratory samples within a ship-
6.4.3 The mounting mechanism of the chainsaw to the
ping container, and between test specimens within a laboratory sample to
bracket shall be fixed.
provide a sampling plan with a meaningful producer’s risk, consumer’s
6.4.4 The guide bar falls perpendicular to the support axis
risk, acceptable quality level, and limiting quality level.
and exerts a static force of 15 N at the point of contact.
8.2 Specimen Preparation:
6.4.5 The vertical dropping distance to the point of contact
8.2.1 The specimen shall be of the same fabric assembly as
with foam is 50 mm (2 in.). The longitudinal axis of the guide
that used in the protective garment. Its technical description
bar is virtually horizontal at the moment of contact (see Figs.
(number of layers, fabric used, etc.) shall be supplied.
3 and 4).
8.2.2 Four holes, 6 mm (0.25 in.) in diameter, shall be
6.4.6 A trigger release mechanism allows freefall without
punched into the specimen in the laboratory at the places
initial acceleration (see Fig. 4 and Fig. 6).
specified. Use these holes to position and to fasten the
6.5 Interfaced Data Acquisition System:
specimen to the test apparatus. Construct a template for
6.5.1 The cutting time between wires placed on the top and
consistency among specimens (Fig. 8).
bottom of the specimen is measured to 60.001 s.
8.3 Number of Specimens:
6.5.1.1 These wires are connected to the circuitry.
8.3.1 Use each specimen only once. Each leg of a paired
6.5.2 The speed of the saw chain may be measured in metres
item can be considered a specimen.
per second or feet per minute (63 %) by means of a magnetic
8.3.2 Use at least three unconditioned specimens to deter-
pickup which reads data from a pickup band that is pressed
mine threshold stopping speed of calibration pads.
onto the clutch housing. This data is then read by a tachometer
8.3.3 Use at least three unconditioned specimens and three
which is calibrated to read this information. Some other
conditioned specimens if this test method is used to determine
effective means may be used to determine chain speed with
the threshold stopping speed of performance pads.
equivalent precision (see Fig. 3).
9. Calibration
The sole source of supply of the saw chain with a pitch of 10 mm (0.40 in.), ⁄8,
9.1 Calibration pads shall be composed of the following:
72LP (73LP) Oregon Type, known to the committee at this time is Blount, Inc., 4909
(1) Top cover layer—no less than 400 denier nylon fabric.
S. E. International Way, PO Box 22127, Portland, OR 97222. If you are aware of
(2) Inner pad layers shall be constructed in the following
alternative suppliers, please provide this information to ASTM International
Headquarters. manner:
F3324 − 19 (2023)
Item Quantity Description
A 1 steel plate 0.25 by 576 by 670 mm
B 2 steel plate 0.25 by 216 by 375 mm
C 2 steel plate 0.25 by 208 by 216 mm
D 1 steel tube 0.75 by ID – 1 mm OD by 172 mm
E 1 aluminum plate 0.5 by 4 by 14.5 mm
F 1 hardwood or white pine 152 by 400 mm
G 2 hinge 3 by 3 by ⁄16 in.
H 1 foam pad 15 by 180 by 360 mm + glue
I 6 threaded rod 0.40 by 16 by 120 mm
J 12 bolt 0.40 by 16 mm
K 8 wood screw 8 by 0.75 mm TR
L 1 steel axle 0.75 mm diameter × 350 threaded 0.75 mm × 10 mm × 80 mm at each end
M 2 pillow block VPS112 valuline browing
N 5 bolt 0.75 by 10 mm
O 1 hex bolt 0.75 by 10 by 70 mm
P 1 square 30 mm × 90 mm × ⁄16 × 75L
Q 1 stopping block 20 mm × 40 mm × 60L
R 1 lever support ⁄16 × 80 mm × 130 mm
S 1 lever 0.25 by 60 by 120 mm
T 1 axle 0.250
U 1 compression spring
V 1 micro-switch
W 1 safety shield pivoting on D
NOTE 1—Measurements are in millimetres. Arcs of a circle are measured on the circumference of the wood cylinder.
FIG. 5 Chainsaw Support Bracket (Side View)
(a) One layer of Lincoln Fabrics woven Kevlar #49
...