Zwilling J.A. Henckels Four Star 11pc Block Set Including 4 Steak Knives Manufactured in Germany Manufactured in Solingen, Germany with ZWILLING Special Formula of high carbon German stainless steel. FRIODUR Tempered Each ZWILLING knife features a FRIODUR blade, icehardened to ~57 Rockwell Hardness. SIGMAFORGE SIGMAFORGE knife, forged from a single piece of steel and is hand sharpened and polished. The edge angle 15 on each side to maintain the cutting edge of the blade.