U.S. Navy UDT Divers Knife. 1961 US Navy SEAL and UDT knife made by Imperial Knife Company.

The Imperial UDT nonmagnetic dive knife was designed for the early Seal teams that were doing UDT work in the early 1960’s and used through Vietnam. The blade is made from a special Haynes Alloy N0.25. Only about 1,156 of these knives were ever made making these very rare amongst U.S. issue knives.