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 6320-01-414-7099
NSN 6645-01-076-4655
NSN 5985-00-919-0677
NSN 6110-01-654-7066
NSN 5935-01-193-5597
NSN 6620-01-391-9829
NSN 4140-01-005-3457
NSN 5910-01-481-4165
NSN 5835-01-013-9321
NSN 2925-01-170-8018
NSN 6650-00-891-9850
NSN 5930-00-265-5822