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 5965-01-483-3200
NSN 4140-01-209-8456
NSN 6135-00-871-3646
NSN 5910-01-137-4211
NSN 6320-00-194-4252
NSN 6220-01-162-6892
NSN 5975-01-281-7692
NSN 5895-00-623-3145
NSN 5996-01-047-4518
NSN 6650-00-242-7961
NSN 5945-01-158-1192
NSN 5985-01-050-8310