ZX4: Hollow construction for exceptional forgiveness Strong and lightweight forged HT1770 steel face offers increased face-flex for greater speed and distance 431 steel body absorbs vibrations for a softer feel Premium, high-density tungsten in base of long and mid irons lowers COG for a high-launch profile MainFrame technology milled into the backside of the face features a variable thickness pattern that maximizes COR for greater ball speed and distance Tour V.T. Sole offers smoother turf interaction and improved impact feel Sharp address view and mid-sized profile Grip: Golf Pride Tour Velvet 360 Game-improvement iron: Medium-sized clubheads with lots of forgiving features while featuring a fairly classic profile at address