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 6150-00-111-0881
NSN 6610-01-539-9084
NSN 6320-01-230-8444
NSN 5975-00-670-5213
NSN 5985-01-462-4200
NSN 5925-01-429-4554
NSN 6610-00-492-9872
NSN 5895-01-010-3102
NSN 5920-00-974-4381
NSN 5915-01-440-3998
NSN 5998-00-853-7566
NSN 5998-01-148-4470