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 6150-01-513-7808
NSN 5950-01-276-0156
NSN 6135-01-193-8154
NSN 5996-01-528-4563
NSN 6610-00-593-5299
NSN 6685-01-534-7192
NSN 6650-01-547-7277
NSN 6220-00-072-7280
NSN 5965-01-651-0092
NSN 5935-01-471-4132
NSN 2925-01-225-0713
NSN 5996-01-072-8378