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 6130-00-617-1934
NSN 6620-00-728-3445
NSN 6240-01-312-6281
NSN 6650-01-415-5573
NSN 5910-00-954-1603
NSN 5920-01-336-4608
NSN 5975-01-522-0822
NSN 4140-01-460-3381
NSN 5996-01-491-0178
NSN 5945-01-170-5768
NSN 6610-00-280-0546
NSN 5935-00-728-0491