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 2925-00-159-9003
NSN 6130-01-234-4549
NSN 6240-00-617-9599
NSN 5985-01-392-5582
NSN 5999-01-088-2364
NSN 5999-00-142-9265
NSN 5960-00-390-9789
NSN 5855-01-305-8524
NSN 6645-00-761-7256
NSN 5950-01-392-6396
NSN 5965-00-882-6949
NSN 5915-01-361-3717