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4221987 — THUMBSCREW

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

4221987: THUMBSCREW.

The THUMBSCREW is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, head_style: THUMB NO. 3, head_height: 0.95 INCHES NOMINAL IN, head_diameter: 0.76 INCHES NOMINAL IN, fastener_length: 1.00 INCHES NOMINAL IN, thread_direction: RIGHT-HAND.

This part is cataloged in the U.S. Government catalog under NSN 5305-01-666-3272, indicating validated use in U.S. government and defense logistics supply chains.

Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels. Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
4221987
NSN: 5305-01-666-3272
FSC: 5305 — Screws
CAGE: 75Q65 — OSHKOSH DEFENSE LLC (USA)
SPECIFICATIONS
materialSTEEL OVERALL
head_styleTHUMB NO. 3
head_height0.95 INCHES NOMINAL IN
head_diameter0.76 INCHES NOMINAL IN
fastener_length1.00 INCHES NOMINAL IN
thread_directionRIGHT-HAND
surface_treatmentPHOSPHATE ZINC OVERALL
width_between_flats0.83 INCHES NOMINAL IN
end_item_identificationMRAP - M-ATV
nominal_thread_diameter0.375 INCHES IN
thread_quantity_per_inch16
thread_series_designatorUNIFIED NATIONAL COARSE (UNC)
NSN5305-01-666-3272
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 4221987 · OEM ⚠ VERIFY BEFORE ORDERING Verify thread pitch before ordering — metric (M8×1.25) ≠ imperial (5/16-18). Wrong thread = wrong part. Grade/class stamped on bolt head determines tensile strength ✓ BROKER TIP Grade/class stamped on head determines tensile strength. Grade 8 > Grade 5 > Grade 2. Always confirm head marking matches specification requirement PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
HEAD HEIGHT: 0.95 INCHES NOMINAL IN
•
FASTENER LENGTH: 1.00 INCHES NOMINAL IN
•
NOMINAL THREAD DIAMETER: 0.375 INCHES IN
•
HEAD STYLE: THUMB NO. 3
•
THREAD DIRECTION: RIGHT-HAND
•
WIDTH BETWEEN FLATS: 0.83 INCHES NOMINAL IN
•
COLOR: BLACK OVERALL
•
SURFACE TREATMENT: PHOSPHATE ZINC OVERALL
TECHNICAL CHARACTERISTICS
HEAD HEIGHT0.95 INCHES NOMINAL IN
FASTENER LENGTH1.00 INCHES NOMINAL IN
NOMINAL THREAD DIAMETER0.375 INCHES IN
HEAD STYLETHUMB NO. 3
THREAD DIRECTIONRIGHT-HAND
WIDTH BETWEEN FLATS0.83 INCHES NOMINAL IN
COLORBLACK OVERALL
SURFACE TREATMENTPHOSPHATE ZINC OVERALL
PART NAME ASSIGNED BY CONTROLLING AGENCYSCREW, THUMB 3/8 - 16 X 1.00 MB MB
END ITEM IDENTIFICATIONMRAP - M-ATV
OTHER ITEMS IN FSC 5305 — Screws
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5305-00-001-5016 5305-00-001-9160 5305-00-001-9629 5305-00-001-9742 5305-00-001-9768 5305-00-003-4306 5305-00-003-6694 5305-00-003-6753
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Insurance item — stocked against contingency demandNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 4221987?
4221987 is a THUMBSCREW.
What is the NSN for 4221987?
4221987 is cataloged in the U.S. Government catalog under NSN 5305-01-666-3272. This indicates validated use in U.S. government and defense supply chains.
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✓ PartsTable — the parts reference. Every fact cited to its source.
PartsTable Design LLC · partstable.com
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.
PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.