This is an extremely rare and sought after U.S. Trench knife model 1918 mark 1, made by Henry Diston & Sohn. HD&S is the rarest of the 1918 knuckle "duster" knives from my research. This blade has a fairly worn handle, where the "H" is not as visible, but is definitely original. The blade itself is very worn as well, but this is uniform throughout the knife and helps confirm the authenticity. The blade has NEVER been apart according to the collector we got this from. Comes with an original scabbard as well which has both belt hooks in tact (very seldom found). Overall a beautiful and scarce grouping.