PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

SS-C-621Concrete Masonry Unit,hollow

Federal Specifications Promulgated by General Services Administration Washington DC · NSN 5620-00-297-5378 · FSC 5620 · No Item Name Available
Verified by PartsTable
NSN 5620-00-297-5378 — this item is cataloged by the U.S. Government under National Stock Number 5620-00-297-5378. Primary manufacturer part number: SS-C-621.
Features
  • Concrete Masonry Unit,hollow — FSC 5620
  • Shell Thickness at Side: 1.312 INCHES NOMINAL IN
  • Style Designator: CORNER HEADER (THREE CELL)
  • Length: 16.000 INCHES NOMINAL IN
  • Nondefinitive Spec/std Data: 1 TYPE AND N GRADE
  • Cell Length: 4.000 INCHES NOMINAL IN
  • Width: 8.000 INCHES NOMINAL IN
  • Cell Width: 5.125 INCHES NOMINAL IN
Applications
  • Building construction and repair
  • Infrastructure development
  • Road and bridge materials
General Description

The Concrete Masonry Unit,hollow, cataloged under National Stock Number 5620-00-297-5378, is classified within Federal Supply Class 5620 (No Item Name Available) of the Construction and Building Materials group. The primary manufacturer of record is Federal Specifications Promulgated by General Services Administration Washington DC. Government technical data includes 10 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 2 commercial cross-references from 2 manufacturers, enabling identification through both NSN and commercial part number lookups. 3 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN5620-00-297-5378
Primary Part NumberSS-C-621
Item NameConcrete Masonry Unit,hollow
FSC / FSG5620 / 56 — No Item Name Available
ManufacturerFederal Specifications Promulgated by General Services Administration Washington DC
StatusACTIVE
Shell Thickness at Side1.312 INCHES NOMINAL IN
Style DesignatorCORNER HEADER (THREE CELL)
Length16.000 INCHES NOMINAL IN
Nondefinitive Spec/std Data1 TYPE AND N GRADE
Cell Length4.000 INCHES NOMINAL IN
Width8.000 INCHES NOMINAL IN
Cell Width5.125 INCHES NOMINAL IN
Height8.000 INCHES NOMINAL IN
Shell Thickness at Exposed Corner End1.312 INCHES NOMINAL IN
Web Thickness1.000 INCHES NOMINAL IN
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 3
5620-01-126-5471080002 INTERCHANGEABLE
Concrete Masonry Unit,hollow
County Materials Corp. Dba County Materials Corp
5620-01-126-5472080027 INTERCHANGEABLE
Concrete Masonry Unit,hollow
County Materials Corp. Dba County Materials Corp
5620-01-679-0338 INTERCHANGEABLE
Brick,building,concrete
Cross-Reference Index
Part NumberManufacturer
SS-C-621 Federal Specifications Promulgated by General Services Administration Washington DC (USA)
ASTM C90 American Society for Testing and Materials Dba Astm International (USA)
Related Parts
5620-01-126-5471INTERCHANGEABLE
CONCRETE MASONRY UNIT,HOLLOW
080002
5620-01-126-5472INTERCHANGEABLE
CONCRETE MASONRY UNIT,HOLLOW
080027
5620-01-679-0338INTERCHANGEABLE
BRICK,BUILDING,CONCRETE

Frequently Asked Questions

What is NSN 5620-00-297-5378?

NSN 5620-00-297-5378 is a Concrete Masonry Unit,hollow, manufactured by Federal Specifications Promulgated by General Services Administration Washington DC, classified under FSC 5620 (No Item Name Available). Status: active.

What are the part numbers for NSN 5620-00-297-5378?

NSN 5620-00-297-5378 has 2 cross-referenced part numbers: SS-C-621 (Federal Specifications Promulgated by General Services Administration Washington DC), ASTM C90 (American Society for Testing and Materials Dba Astm International).

What NSN replaces 5620-00-297-5378?

There are 3 known substitutes for 5620-00-297-5378: 5620-01-126-5471, 5620-01-126-5472, 5620-01-679-0338. Verify interchangeability with system specifications before substitution.

What are the specifications of SS-C-621?

Key specifications for SS-C-621: Shell Thickness at Side: 1.312 INCHES NOMINAL IN; Style Designator: CORNER HEADER (THREE CELL); Length: 16.000 INCHES NOMINAL IN; Nondefinitive Spec/std Data: 1 TYPE AND N GRADE. 10 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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