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 5990-01-147-8097
NSN 6220-00-956-0565
NSN 5965-00-849-1313
NSN 6685-01-151-8093
NSN 5999-00-904-4210
NSN 5930-00-456-6698
NSN 6110-01-644-5104
NSN 5999-00-752-7655
NSN 6645-01-051-7447
NSN 5996-00-058-3089
NSN 5950-00-164-0442
NSN 6130-00-738-7290