U.S. Military Surplus A US Navy ND series gas mask from the 1940s, during World War II. The Navy, which had not previously had its own gas masks, began with the Optical Gas Mask as dedicated equipment, and evolved over time to Mark 1 to Mark 5. This is Mark 4 of that series. The official name is USN U GAS MASK ND MARK Ⅳ. The main flap and both side flaps are fastened with buttons, and the inside has one partition and a belt to secure the anti-fogging canister. One-sided hook-type shoulder strap. There are minor stains commensurate with its age, but no tears or holes, and the printing is clear. Compared to similar items, the condition is quite good. The metal fittings on the shoulder strap have no paint剥がれ (peeling). Although many items have inscriptions, this one is completely undamaged. External dimensions: Approximately 22x26x20 cm Strap length: Approximately 140 cm maximum