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 6220-00-284-3220
NSN 6130-01-634-0603
NSN 5895-01-060-7991
NSN 5935-01-654-4784
NSN 5855-01-513-1859
NSN 5998-01-430-1888
NSN 5945-00-146-4909
NSN 5975-01-086-3423
NSN 5920-01-496-2513
NSN 5930-00-980-0402
NSN 5998-01-247-9593
NSN 6130-01-275-1738