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 5925-01-191-4285
NSN 5915-01-149-5343
NSN 2925-01-556-0333
NSN 6145-01-151-0238
NSN 6610-00-277-7206
NSN 6130-00-381-1927
NSN 4140-00-106-6780
NSN 5965-00-959-4910
NSN 2925-01-618-2458
NSN 6130-01-323-2500
NSN 5965-01-109-2917
NSN 5905-00-936-8402