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638A544 — SCREW,CAP,HEXAGON HEAD

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

638A544: SCREW,CAP,HEXAGON HEAD.

The SCREW,CAP,HEXAGON HEAD is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, head_style: HEXAGON, head_height: 0.125 INCHES NOMINAL IN, thread_class: 2A A, thread_length: 0.438 INCHES NOMINAL IN, fastener_length: 0.750 INCHES NOMINAL IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-01-169-9103, 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
638A544
NSN: 5305-01-169-9103
FSC: 5305 — Screws
CAGE: 01289 — GENERAL ELECTRIC COMPANY (USA)
SPECIFICATIONS
materialSTEEL OVERALL
head_styleHEXAGON
head_height0.125 INCHES NOMINAL IN
thread_class2A A
thread_length0.438 INCHES NOMINAL IN
fastener_length0.750 INCHES NOMINAL IN
thread_directionRIGHT-HAND
width_between_flats0.375 INCHES NOMINAL IN
nominal_thread_diameter0.250 INCHES IN
thread_quantity_per_inch20
thread_series_designatorUNIFIED NATIONAL COARSE (UNC)
material_document_and_classificationB4A2F,CAGEC 01289 MFR REF SINGLE MATERIAL RESPONSE OVERALL
NSN5305-01-169-9103
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 638A544 · 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: 0.125 INCHES NOMINAL IN
•
FASTENER LENGTH: 0.750 INCHES NOMINAL IN
•
THREAD LENGTH: 0.438 INCHES NOMINAL IN
•
MATERIAL DOCUMENT AND CLASSIFICATION: B4A2F,CAGEC 01289 MFR REF SINGLE MATERIAL RESPONSE OVERALL
•
NOMINAL THREAD DIAMETER: 0.250 INCHES IN
•
HEAD STYLE: HEXAGON
•
THREAD DIRECTION: RIGHT-HAND
•
WIDTH BETWEEN FLATS: 0.375 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS
HEAD HEIGHT0.125 INCHES NOMINAL IN
FASTENER LENGTH0.750 INCHES NOMINAL IN
THREAD LENGTH0.438 INCHES NOMINAL IN
MATERIAL DOCUMENT AND CLASSIFICATIONB4A2F,CAGEC 01289 MFR REF SINGLE MATERIAL RESPONSE OVERALL
NOMINAL THREAD DIAMETER0.250 INCHES IN
HEAD STYLEHEXAGON
THREAD DIRECTIONRIGHT-HAND
WIDTH BETWEEN FLATS0.375 INCHES NOMINAL IN
THREAD CLASS2A A
THREAD QUANTITY PER INCH20
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 1
638A544 PIECE 1Reference document
Same NSN cross-reference
Reference document — Advisory reference — outside the item-of-supply concept
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 638A544?
638A544 is a SCREW,CAP,HEXAGON HEAD.
What parts can replace 638A544?
There is 1 known substitute for 638A544: 638A544 PIECE 1. Substitute compatibility should be verified for your specific system.
What is the NSN for 638A544?
638A544 is cataloged in the U.S. Government catalog under NSN 5305-01-169-9103. 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.