These are unfinished folding knife parts from the Seizo Imai factory in Seki, Japan made circa 1990s. The blade is rough ground and has not been heat treated/hardened. It is made of ATS-34 and comes with backspring and spacer. These need finished, fitting, and assembly. Only pictured parts are included, will need other parts to complete. The blade measures 3-15/16" long overall and measures 0.138" thick. This is the Blackjack Mamba pattern, please see the last picture to see one as completed by Imai (not included). Seizo Imai was one of Seki, Japan's finest craftsmen and most famous knifemakers of the modern era. His collaboration with Parker spanned nearly two decades. He also made knives for Frost, Browning, Explorer, Compass, Condor, and many others, including his own brands Imax and Seizo Imai. His custom Loveless style knives are works of art. After his passing, several vintage old stock models were found at his warehouse. This is one of these rare finds.