The Endurance Blade is made with a proprietary stainless steel metal chemistry with the ability to retain its edge longer than our traditional blades. 2x More Cuts Per Blade. Retains cutting edge two times longer while cutting fabrics before dulling. Innovative engineering. Proprietary tungsten steel metal chemistry with innovative heat treatment process for exceptional durable long life. High performance cutting edge Proprietary sharpening process for the industry benchmark in cutting. Compatible with all current OLFA cutter handles.