The 2017 Callaway Great Big Bertha (that's what GBB stands for!) Epic Sub Zero Driver heralds a true paradigm shift: a powerful, low-spinning Tour-level driver that�s also incredibly forgiving. It's an unheard of combination. Epic Sub Zero is so exceptionally forgiving and easy to launch that a wide range of players will want to play it. The key to Epic Sub Zero�s breakthrough performance is the patent-pending Jailbreak Technology, which profoundly changes how the head and face behave to increase ball speed and distance. Jailbreak positions two ultra-light (3 gram) and ultra-strong titanium bars behind the face, connected to the crown and sole. Jailbreak bars reduce crown and sole deflection, allowing the face to take on more impact-load. Standard Callaway warranty applies and your satisfaction is guaranteed. Callaway headcover and wrench included. Nearly endless customization is available, so don't be afraid to ask!