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 5965-01-509-3841
NSN 6320-00-593-0379
NSN 5925-01-463-8594
NSN 6645-01-394-5149
NSN 6130-00-146-8009
NSN 6150-01-105-9635
NSN 5930-01-583-0841
NSN 6610-01-400-3880
NSN 5895-01-394-5469
NSN 6650-00-193-7358
NSN 5998-00-035-5308
NSN 2925-01-442-4171