This is a very rare Thommes Diving knife believed to have been made by Wenoka in Seki, Japan for retail sale in Europe. Perhaps from the Norwegian dive school founded by Jan-Thommes Thomassen in 1954 (difficult to find information on it). It is very heavy duty and features a 0.232" thick blade and has a molded dense plastic handle with a steel pommel. The grip is designed to provide maximum retention in the hand. The Rostfrei marking is partially worn off. Comes in a nylon sheath which is not original but a nice fit.