5680-01-034-7560 (MIL-C-7438)
NSN 5680-01-034-7560 (NIIN 01-034-7560) is a structura cellular core material in Federal Supply Class 5680, Miscellaneous Construction Materials — a light durable material having a cellular core of uniform geometric shapes. Manufacturer part number MIL-C-7438 (Military Specifications, CAGE 81349); also referenced as 5.7 3/16.0020 5056 3.5X20X36 (American Cyanamid Co Industrial).
Key specs: 5.7 lb per cu ft nominal density; full characteristics table below. NIIN assigned January 1977; DEMIL A (none required).