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PartsTable / COMPONENT / C3998-4-4
C3998-4-4 ✓ Verified by PartsTable
— · BOLT SCREW
WHAT YOU NEED TO KNOW
Grade/class stamped on head determines strength Metric and imperial threads look similar — measure pitch
Verify thread pitch — metric != imperial
PRODUCT OVERVIEW

The SCREW,SHOULDER is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, head_style: PAN NO. 2, head_height: 0.094 INCHES MINIMUM AND 0.156 INCHES MAXIMUM IN, thread_class: 2A A, head_diameter: 0.344 INCHES MINIMUM AND 0.406 INCHES MAXIMUM IN, thread_length: 0.219 INCHES MINIMUM AND 0.281 INCHES MAXIMUM IN.

This product is currently in active production with full OEM support. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5305-01-218-3163, 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
C3998-4-4
NSN: 5305-01-218-3163
FSC: 5305
CAGE: 81755 — LOCKHEED MARTIN CORPORATION DIV LOCKHEED MARTIN AERONAUTICS COMPANY (USA)
SPECIFICATIONS
materialSTEEL OVERALL
head_stylePAN NO. 2
head_height0.094 INCHES MINIMUM AND 0.156 INCHES MAXIMUM IN
thread_class2A A
head_diameter0.344 INCHES MINIMUM AND 0.406 INCHES MAXIMUM IN
thread_length0.219 INCHES MINIMUM AND 0.281 INCHES MAXIMUM IN
shoulder_shapeROUND FIRST SHOULDER
fastener_length0.344 INCHES MINIMUM AND 0.406 INCHES MAXIMUM IN
shoulder_length0.094 INCHES MINIMUM AND 0.156 INCHES MAXIMUM FIRST SHOULDER IN
thread_directionRIGHT-HAND
shoulder_diameter0.219 INCHES MINIMUM AND 0.281 INCHES MAXIMUM FIRST SHOULDER IN
internal_drive_styleSLOT
NSN5305-01-218-3163
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: C3998-4-4 · 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
•
SHOULDER LENGTH: 0.094 INCHES MINIMUM AND 0.156 INCHES MAXIMUM FIRST SHOULDER IN
•
THREAD SERIES DESIGNATOR: UNF
•
NOMINAL THREAD DIAMETER: 0.190 INCHES IN
•
THREAD QUANTITY PER INCH: 32
•
SHOULDER DIAMETER: 0.219 INCHES MINIMUM AND 0.281 INCHES MAXIMUM FIRST SHOULDER IN
•
MATERIAL: STEEL OVERALL
•
THREAD LENGTH: 0.219 INCHES MINIMUM AND 0.281 INCHES MAXIMUM IN
•
THREAD CLASS: 2A A
TECHNICAL CHARACTERISTICS (FLIS)
SHOULDER LENGTH0.094 INCHES MINIMUM AND 0.156 INCHES MAXIMUM FIRST SHOULDER IN
THREAD SERIES DESIGNATORUNF
NOMINAL THREAD DIAMETER0.190 INCHES IN
THREAD QUANTITY PER INCH32
SHOULDER DIAMETER0.219 INCHES MINIMUM AND 0.281 INCHES MAXIMUM FIRST SHOULDER IN
MATERIALSTEEL OVERALL
THREAD LENGTH0.219 INCHES MINIMUM AND 0.281 INCHES MAXIMUM IN
THREAD CLASS2A A
INTERNAL DRIVE STYLESLOT
SHOULDER SHAPEROUND FIRST SHOULDER
VERIFIED SUBSTITUTES & CROSS-REFERENCES 5
00012800206285Interchangeable
interchangeable cross-reference
interchangeable
926Interchangeable
interchangeable cross-reference
interchangeable
TW2Interchangeable
interchangeable cross-reference
interchangeable
68D320014-2083Interchangeable
interchangeable cross-reference
interchangeable
ST3M536-3Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is C3998-4-4?
C3998-4-4 is a SCREW,SHOULDER.
What parts can replace C3998-4-4?
There are 5 known substitutes for C3998-4-4: 00012800206285, 926, TW2 and 2 more. Substitute compatibility should be verified for your specific system.
What is the NSN for C3998-4-4?
C3998-4-4 is cataloged in the Federal Logistics Information System (FLIS) under NSN 5305-01-218-3163. This indicates validated use in U.S. government and defense supply chains.
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PartsTable Design LLC · partstable.com
Last verified: July 2026