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 5999-01-503-1519
NSN 6110-01-644-5923
NSN 5925-01-446-1967
NSN 6105-01-107-4846
NSN 6610-01-487-6843
NSN 5975-01-606-8238
NSN 5930-01-050-9102
NSN 6130-00-316-3219
NSN 5998-01-623-4574
NSN 5950-00-859-3359
NSN 5965-01-348-8302
NSN 5996-00-025-8026