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 5910-01-146-6685
NSN 6650-01-510-9488
NSN 6610-01-043-5162
NSN 6685-01-649-8166
NSN 5998-01-536-4024
NSN 5935-01-555-8874
NSN 6650-01-272-8864
NSN 5996-01-036-2497
NSN 5996-00-441-9569
NSN 5915-01-590-1575
NSN 6135-01-010-0891
NSN 5835-01-024-0406