Ping G730 7/Irons Steel Set 5-Pw,UwPING G730 Technology Powerful Sound The cavity back design is supplemented with the proven PurFlex cavity badge that enhances feel and produces a more powerful sound. Multiple flex zones allow for more free bending to increase ball speed across the face for longer results. Flexing Face By employing hyper 17 4 stainless steel through heat treating, we thinned the face and optimized its overall structure to increase flexing and help lower the CG,