I think I got this off their website. I gave my Eggen to a nephew to use in Scouts, but I liked that blade a lot. Very light, great for backpacking, took a very good edge: Most Helle blades are made of triple laminate stainless steel, a sandwich of tough stainless panels with a core of high carbon steel. It is especially made for Helle, and does not correspond to any of the standard types of steel. High carbon steel is tougher than stainless, easier to sharpen and holds a superior edge. For the technically minded, the composition of the high carbon steel core is: Carbon -0.67%, Silicon -0.70%, Sulphur -0.002%, Phosphorous -0.19%, Manganese 0.44%, Nickel -0.28%, Chromium -0.28%, Molybdenum -0.52%. The high carbon steel core is hardened to 58-59 HRC (Rockwell Scale). This is the harder part of the blade that holds the edge.
The outside layers are tough 18/8 stainless, 18% chromium and 8% nickel. Together, this makes a blade that can be sharpened to a very fine razor edge, and yet is not brittle. It is also easier to re-sharpen than conventional knives because much of the steel being removed (the outer panels) is softer than standard cutlery steel. This type of blade will bend long before it would break.