A rigid item designed to frame a structural opening for reinforcement purposes and/or to accommodate covers, access (as modified) and doors, access (as modified).
NSN 5985-01-448-9396
NSN 5920-01-620-3023
NSN 7035-00-153-3826
NSN 5925-01-397-1460
NSN 5999-01-111-0001
NSN 6145-00-323-6021
NSN 5935-01-176-4735
NSN 5975-01-094-6943
NSN 6650-01-562-6772
NSN 5915-00-816-9056
NSN 5945-00-162-1860
NSN 6685-01-303-4673