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 6685-00-161-5752
NSN 5999-00-019-0139
NSN 6650-01-607-1283
NSN 5925-01-021-1045
NSN 6135-00-010-5275
NSN 5915-00-167-9629
NSN 6610-00-895-3854
NSN 7035-00-616-4410
NSN 5835-00-554-0399
NSN 6145-01-030-3400
NSN 5925-00-224-7474
NSN 6620-01-145-1278