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 6130-01-445-5878
NSN 5945-00-929-7159
NSN 6645-01-214-6309
NSN 6610-01-179-8352
NSN 5996-00-104-8293
NSN 5990-01-442-3520
NSN 5905-01-023-9003
NSN 4140-00-587-7496
NSN 6105-01-286-6807
NSN 5998-01-451-4078
NSN 5835-01-079-8865
NSN 6150-01-578-6786