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 5930-01-348-7197
NSN 6150-01-520-9628
NSN 6105-01-358-2081
NSN 5960-01-570-8605
NSN 5998-00-005-8781
NSN 5950-00-028-3512
NSN 6220-01-628-5417
NSN 6150-00-862-1081
NSN 5965-01-337-5408
NSN 2925-01-197-7864
NSN 6110-00-472-0782
NSN 6105-01-501-6395