Callaway® Hyper X driver. The driver's hyperbolic face technology dramatically improves impact efficiency and produces a large effective hitting area, generating higher ball speeds across the entire face. The modified x-sole design even helps provide proper alignment at address so more drives start on the intended target line. Hyperbolic face technology dramatically improves impact efficiency and produces a large effective hitting area, generating higher ball speeds across the entire face for significant average distance gains on off-center hits Modified x-sole design helps provide proper alignment at address so more drives start on the intended target line Optimized head shape provides a high MOI (moment of inertia) for increased forgiveness and stability on mis-hits S2H2 design increases discretionary weight by removing it from the hosel and repositioning it in the perimeter of the clubhead