I have an older Police Model that I've been carrying for a long time. It's a left-handed, plain-edge, that I would guess I bought around 1990. It was special ordered by the knife shop at the time. The words "POLICE MODEL" are etched into the upper part of the blade in bold type-face, and the words "SEKI-JAPAN" are etched into the base of the same side of the blade. The word "SPYDERCO" is etched into the other side's base of the blade. Can anyone tell me what type of steel this blade is made from? Thanks in advance for any replies.