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SI668A9D — WASHER,FINISHING

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

SI668A9D: WASHER,FINISHING.

The WASHER,FINISHING is a the manufacturer industrial component. Key specifications include material: ALUMINUM ALLOY 2024 OVERALL, recess_angle: 100.0 DEGREES NOMINAL, hole_diameter: 0.185 INCHES MINIMUM AND 0.195 INCHES MAXIMUM IN, overall_height: 0.068 INCHES MINIMUM AND 0.078 INCHES MAXIMUM IN, recess_diameter: 0.385 INCHES MINIMUM AND 0.395 INCHES MAXIMUM IN, outside_diameter: 0.557 INCHES MINIMUM AND 0.582 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5310-00-409-9921, 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
SI668A9D
NSN: 5310-00-409-9921
FSC: 5310 — Nuts and Washers
CAGE: 24434 — SKYLINE INDUSTRIES, INC (USA)
SPECIFICATIONS
materialALUMINUM ALLOY 2024 OVERALL
recess_angle100.0 DEGREES NOMINAL
hole_diameter0.185 INCHES MINIMUM AND 0.195 INCHES MAXIMUM IN
overall_height0.068 INCHES MINIMUM AND 0.078 INCHES MAXIMUM IN
recess_diameter0.385 INCHES MINIMUM AND 0.395 INCHES MAXIMUM IN
outside_diameter0.557 INCHES MINIMUM AND 0.582 INCHES MAXIMUM IN
style_designatorFINISHING
material_thickness0.010 INCHES NOMINAL IN
material_document_and_classificationQQ-A-250/5,T3 FED SPEC SINGLE MATERIAL RESPONSE OR QQ-A-250/5,T4 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
NSN5310-00-409-9921
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: SI668A9D · OEM ⚠ VERIFY BEFORE ORDERING Grade matters for torque spec — don't mix grades. A Grade 5 nut on a Grade 8 bolt weakens the joint. Lock nuts, wing nuts, and castle nuts are NOT interchangeable with standard hex ✓ BROKER TIP Match nut to bolt thread class and material. Stainless bolt + zinc nut = galvanic corrosion. Always verify finish matches (plain, zinc, hot-dip galvanized) PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
STYLE DESIGNATOR: FINISHING
•
MATERIAL DOCUMENT AND CLASSIFICATION: QQ-A-250/5,T3 FED SPEC SINGLE MATERIAL RESPONSE OR QQ-A-250/5,T4 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
•
OUTSIDE DIAMETER: 0.557 INCHES MINIMUM AND 0.582 INCHES MAXIMUM IN
•
MATERIAL THICKNESS: 0.010 INCHES NOMINAL IN
•
RECESS DIAMETER: 0.385 INCHES MINIMUM AND 0.395 INCHES MAXIMUM IN
•
MATERIAL: ALUMINUM ALLOY 2024 OVERALL
•
HOLE DIAMETER: 0.185 INCHES MINIMUM AND 0.195 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS
OVERALL HEIGHT0.068 INCHES MINIMUM AND 0.078 INCHES MAXIMUM IN
STYLE DESIGNATORFINISHING
MATERIAL DOCUMENT AND CLASSIFICATIONQQ-A-250/5,T3 FED SPEC SINGLE MATERIAL RESPONSE OR QQ-A-250/5,T4 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
OUTSIDE DIAMETER0.557 INCHES MINIMUM AND 0.582 INCHES MAXIMUM IN
MATERIAL THICKNESS0.010 INCHES NOMINAL IN
RECESS DIAMETER0.385 INCHES MINIMUM AND 0.395 INCHES MAXIMUM IN
MATERIALALUMINUM ALLOY 2024 OVERALL
HOLE DIAMETER0.185 INCHES MINIMUM AND 0.195 INCHES MAXIMUM IN
RECESS ANGLE100.0 DEGREES NOMINAL
OTHER ITEMS IN FSC 5310 — Nuts and Washers
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5310-00-000-0040 5310-00-000-0077 5310-00-000-0079 5310-00-000-1146 5310-00-000-3815 5310-00-000-4532 5310-00-000-4540
SUBSTITUTES & CROSS-REFERENCES 2
CG599A9DSame NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
C668A9DReference document
Same NSN cross-reference
Reference document — Vendor item drawing reference
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 SI668A9D?
SI668A9D is a WASHER,FINISHING.
What parts can replace SI668A9D?
There are 2 known substitutes for SI668A9D: CG599A9D, C668A9D. Substitute compatibility should be verified for your specific system.
What is the NSN for SI668A9D?
SI668A9D is cataloged in the U.S. Government catalog under NSN 5310-00-409-9921. 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.