Callaway Men's Big Bertha Alpha 815 Double Black Diamond Golf Driver RMOTO: A cool name and even better distance technology MULTI MATERIAL CONSTRUCTION: All the best, most important driver technology has gone into this club GRAVITY CORE: Our patented 3D CG adjustment lets you flip the core up or down TOUR PREMIUM SHAFTS & Head Design: An Aldila Rogue 60 or new Matrix Ozik Black Tie 70 OPTIFIT TECHNOLOGY: Callaway adjustability at its finest