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4B21S4-101 — BEARING,SLEEVE

✓ Government record, cited
— · BALL BEARING
PRODUCT OVERVIEW

4B21S4-101: BEARING,SLEEVE.

The BEARING,SLEEVE is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, corner_shape: SQUARE ALL CORNERS, overall_length: 1.0262 INCHES MINIMUM AND 1.0312 INCHES MAXIMUM IN, surface_finish: 125.0 MICROINCHES LEFT END SURFACE OF BODY, style_designator: SOLID, PLAIN, NO OUTSIDE FLANGES, surface_treatment: CHROMIUM OUTSIDE DIAMETER SURFACE OF BODY. This part is cataloged in the U.S.

Government catalog under NSN 3120-00-293-5451, 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
4B21S4-101
NSN: 3120-00-293-5451
FSC: 3120 — Bearings, Plain, Unmounted
CAGE: 43999 — THE BOEING COMPANY DIV LEGACY AM&M (USA)
SPECIFICATIONS
materialSTEEL OVERALL
corner_shapeSQUARE ALL CORNERS
overall_length1.0262 INCHES MINIMUM AND 1.0312 INCHES MAXIMUM IN
surface_finish125.0 MICROINCHES LEFT END SURFACE OF BODY
style_designatorSOLID, PLAIN, NO OUTSIDE FLANGES
surface_treatmentCHROMIUM OUTSIDE DIAMETER SURFACE OF BODY
body_inside_diameter0.2495 INCHES MINIMUM AND 0.2505 INCHES MAXIMUM IN
body_outside_diameter0.3730 INCHES MINIMUM AND 0.3735 INCHES MAXIMUM IN
NSN3120-00-293-5451
COMPONENT DIAGRAM
BALL BEARING — SEAL TYPE DETERMINES MAINTENANCE OD: — · BORE: — · WIDTH: — SEAL: Open · PN: 4B21S4-101 · OEM ⚠ VERIFY BEFORE ORDERING ABEC grade: higher = tighter tolerance = higher cost. ABEC-1 is standard, ABEC-7+ for precision spindles. Open, shielded (ZZ), and sealed (2RS) versions have different max RPM ratings ✓ BROKER TIP 2RS = sealed for life (no maintenance). ZZ = shielded, re-greaseable. Open = must lubricate on install. Common interchange: 6205-2RS = 6205-2RSR = 6205-DDU (same bearing, different suffix) PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
SURFACE FINISH: 16.0 MICROINCHES OUTSIDE DIAMETER SURFACE OF BODY
•
CORNER SHAPE: SQUARE ALL CORNERS
•
BODY OUTSIDE DIAMETER: 0.3730 INCHES MINIMUM AND 0.3735 INCHES MAXIMUM IN
•
STYLE DESIGNATOR: SOLID, PLAIN, NO OUTSIDE FLANGES
TECHNICAL CHARACTERISTICS
SURFACE FINISH16.0 MICROINCHES OUTSIDE DIAMETER SURFACE OF BODY
SURFACE FINISH125.0 MICROINCHES RIGHT END SURFACE OF BODY
SURFACE FINISH250.0 MICROINCHES INSIDE DIAMETER SURFACE OF BODY
SURFACE FINISH125.0 MICROINCHES LEFT END SURFACE OF BODY
CORNER SHAPESQUARE ALL CORNERS
BODY OUTSIDE DIAMETER0.3730 INCHES MINIMUM AND 0.3735 INCHES MAXIMUM IN
STYLE DESIGNATORSOLID, PLAIN, NO OUTSIDE FLANGES
OVERALL LENGTH1.0262 INCHES MINIMUM AND 1.0312 INCHES MAXIMUM IN
BODY INSIDE DIAMETER0.2495 INCHES MINIMUM AND 0.2505 INCHES MAXIMUM IN
SURFACE TREATMENTCHROMIUM OUTSIDE DIAMETER SURFACE OF BODY
OTHER ITEMS IN FSC 3120 — Bearings, Plain, Unmounted
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
3120-00-001-1288 3120-00-001-1835 3120-00-001-1838 3120-00-001-1928 3120-00-001-1934 3120-00-001-3933 3120-00-001-3937 3120-00-001-3938
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Terminal item — no further procurement; issued until stock is exhaustedNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 4B21S4-101?
4B21S4-101 is a BEARING,SLEEVE.
What is the NSN for 4B21S4-101?
4B21S4-101 is cataloged in the U.S. Government catalog under NSN 3120-00-293-5451. 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.