Rockstead SAI blade are made from ZDP189 with a convex blade shape (HONZUKURI). The ZDP-189 is high carbon powder stainless steel produced by Hitachi Metals Co.,Ltd. The ZDP-189 is a stainless steel , but there is a 3% of carbon in it, so we recommend that you wipe blade dry after using, just in case to prevent a extremely small rust points . Blade surface roughness is only 0.0045 microns. Rockstead company are proud that they finally achieved such a surface in the steel material more than 67 Rhc hardness. Handles for this model were made from anodised (99.2% purity ) grade of titanium. High purity titanium is very heavy material for machining. Rocksteady's engineers had to solve a lot of problems during machining process, but corrosion resistance and tensile strength is the highest among the possible choices of titanium grades. Color of the handle is blue. Rockstead SAI is a high-end knife in all meanings.