PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

MS21921-4WNut,tube Coupling

Sae International Dba Sae International · NSN 4730-01-667-6443 · FSC 4730 · No Item Name Available
Verified by PartsTable
NSN 4730-01-667-6443 — this item is cataloged by the U.S. Government under National Stock Number 4730-01-667-6443. Primary manufacturer part number: MS21921-4W.
Features
  • Nut,tube Coupling — FSC 4730
  • Nominal Thread Size: 0.4375 INCHES IN
  • Thread Class: 3B
  • Nominal Tube Outside Diameter: 0.250 INCHES IN
  • Width Across Flats: 0.558 INCHES MINIMUM AND 0.565 INCHES MAXIMUM IN
  • Thread Series: UNIFIED NATIONAL JOINT FINE (UNJF)
  • Thread Direction: RIGHT-HAND
  • Thread Quantity Per Inch: 20.0
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Fluid conveyance
  • Hydraulic system plumbing
General Description

The Nut,tube Coupling, cataloged under National Stock Number 4730-01-667-6443, is classified within Federal Supply Class 4730 (No Item Name Available) of the Pipe, Tubing, Hose, and Fittings group. The primary manufacturer of record is Sae International Dba Sae International. Government technical data includes 12 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 4 commercial cross-references from 2 manufacturers, enabling identification through both NSN and commercial part number lookups. 1 verified substitute exists in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN4730-01-667-6443
Primary Part NumberMS21921-4W
Item NameNut,tube Coupling
FSC / FSG4730 / 47 — No Item Name Available
ManufacturerSae International Dba Sae International
StatusACTIVE
Nominal Thread Size0.4375 INCHES IN
Thread Class3B
Nominal Tube Outside Diameter0.250 INCHES IN
Width Across Flats0.558 INCHES MINIMUM AND 0.565 INCHES MAXIMUM IN
Thread SeriesUNIFIED NATIONAL JOINT FINE (UNJF)
Thread DirectionRIGHT-HAND
Thread Quantity Per Inch20.0
Seat Angle45.0 DEGREES NOMINAL
Smallest Inside Diameter0.300 INCHES MINIMUM AND 0.305 INCHES MAXIMUM IN
Nut StyleTUBE COUPLING
Nut Height0.72 INCHES NOMINAL IN
MaterialALUMINUM ALLOY OVERALL
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 1
4730-00-222-8636MS21921W4 INTERCHANGEABLE
Nut,tube Coupling
Sae International Dba Sae International
Cross-Reference Index
Part NumberManufacturer
MS21921-4W PRIMARY Sae International Dba Sae International (USA)
AS21921-4W Sae International Dba Sae International (USA)
SAE-AS18280 Sae International Dba Sae International (USA)
AS21921-4W Society of Automotive Engineers Inc (USA)
Related Parts
4730-00-222-8636INTERCHANGEABLE
NUT,TUBE COUPLING
MS21921W4

Frequently Asked Questions

What is NSN 4730-01-667-6443?

NSN 4730-01-667-6443 is a Nut,tube Coupling, manufactured by Sae International Dba Sae International, classified under FSC 4730 (No Item Name Available). Status: active.

What are the part numbers for NSN 4730-01-667-6443?

NSN 4730-01-667-6443 has 4 cross-referenced part numbers: MS21921-4W (Sae International Dba Sae International), AS21921-4W (Sae International Dba Sae International), SAE-AS18280 (Sae International Dba Sae International), AS21921-4W (Society of Automotive Engineers Inc).

What NSN replaces 4730-01-667-6443?

There is 1 known substitute for 4730-01-667-6443: 4730-00-222-8636. Verify interchangeability with system specifications before substitution.

What are the specifications of MS21921-4W?

Key specifications for MS21921-4W: Nominal Thread Size: 0.4375 INCHES IN; Thread Class: 3B; Nominal Tube Outside Diameter: 0.250 INCHES IN; Width Across Flats: 0.558 INCHES MINIMUM AND 0.565 INCHES MAXIMUM IN. 13 total characteristics are documented in the Federal Logistics Information System.

Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
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