Multi-layered face: Ultra thin face with an oval center and milled perimeter, creating the highest C.T. Characteristic Time allowed by the USGA in an iron. Two-piece head design: 1) 17-4 cast, stainless steel body; 2) Freely-suspended, high-strength precision milled C455 ultra thin sheet face. Progressive Offset & sole width less on short irons, more on long irons. NEW ProSilver ultra light steel shaft by FST - a revolutionary sub-100 gram shaft with superior launch and spin characteristics. Curvature Matching - Exact bend profile along the entire shaft. Optiflight technology - Engineered to have consistent tip angle changes from club to club for optimal ball launch and flight distance.