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 6130-01-455-1747
NSN 5915-01-469-7568
NSN 7035-01-038-9970
NSN 5920-00-285-2245
NSN 6135-01-293-3066
NSN 6645-00-907-1165
NSN 5999-01-387-5960
NSN 2925-01-099-7075
NSN 6150-01-057-9595
NSN 5835-01-408-7576
NSN 5855-00-003-6408
NSN 6135-00-519-1325