Callaway GBB Epic/Sub Zero/Star

The Epic family of drivers, Callaway's most successful launch since the 1990s, set out to change how drivers flex. Two titanium bars behind the face connect the crown to the sole, keeping the flexing at impact confined to the face. The result is maximum ball speed across a wider area of the face. Lightweight composite pieces in the crown and sole freed up mass for a rear sliding weight on the sole in the standard model, and front and back weights in the lower-spinning Sub Zero. The newest addition is the Star, which uses a shaft that's about a third lighter than typical shafts to help provide extra swing speed.