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 7035-00-535-8109
NSN 5905-00-289-9898
NSN 6610-01-212-2969
NSN 6135-01-432-1002
NSN 5998-00-506-7445
NSN 5999-01-322-8547
NSN 5975-01-091-6161
NSN 5920-01-514-6841
NSN 6105-01-214-1844
NSN 5990-01-343-2187
NSN 6150-01-141-2916
NSN 6320-01-067-0474