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 5920-01-594-4708
NSN 5925-01-425-2326
NSN 5835-01-013-9321
NSN 6645-01-005-8622
NSN 6135-01-459-6424
NSN 5950-01-012-5414
NSN 5965-01-435-6644
NSN 6610-00-624-4494
NSN 5985-00-365-5524
NSN 6135-00-062-5080
NSN 6650-01-546-7632
NSN 6650-01-328-8363