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 5895-00-071-9742
NSN 6135-00-926-3503
NSN 5990-01-091-9595
NSN 5945-00-754-3888
NSN 5985-00-863-0450
NSN 6320-00-394-8458
NSN 6150-00-701-7880
NSN 5985-01-522-1648
NSN 5996-01-378-7636
NSN 5950-00-283-6645
NSN 6610-01-212-2969
NSN 6240-01-443-0519