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 5999-01-422-2065
NSN 5915-01-321-0284
NSN 6320-01-536-3077
NSN 2925-01-197-7864
NSN 7035-01-429-0431
NSN 5990-00-869-2122
NSN 6145-01-216-4388
NSN 5935-01-271-2152
NSN 5998-00-365-8887
NSN 6110-00-366-9229
NSN 6645-00-825-5677
NSN 2925-01-197-7864