All around the fly z xl womens combo set delivers exceptional distance forgiveness and easy up performancethe fly z xl womens combo set combines two different cavity designs wedges ndash 9i incorporate a traditional undercut design for precision and control for the golfer while the 8i 4i feature a duel cavity hollow design that results in a low back center of gravity enabling the golfer to hit it higher and farther the combo set which includes the dual cavity design hollow and cavity