The Titleist Forged 660 irons feature a concave muscle back design. With its progressive, concave muscle and dual hosel length design, Forged 660 irons produce a flighted trajectory through the set for higher-launch long irons, medium launch mid irons, and flat launch short irons. A precision forging process guarantees consistent head shapes, dimensions and weights through the set with the soft feel and sound preferred by better golfers. A glare-reducing satin finish reflects 40% less light than bright chrome. The 660 is made of Forged 1025 Mild Carbon Steel with a glare-reducing satin chrome finish.