8/18/21 - This is a rare US Navy non-magnetic diving knife from the Vietnam era. The knife is maker stamped by Imperial on the hand guard, as shown. This is the 1961 model (1st model), where only approx. 1100 were made. The blade and scabbard are both matching numbered with a laser-etched "M 2-73". The scabbard and blade are both in excellent condition - nicer than any example we've seen. There aren't any unsightly inspector markings or writing on the handle and scabbard, as we've seen on other examples. The blade is unsharpened and only has some mild scabbard wear.