Callaway gbb epic drivers use jailbreak technology and higher moi for increased performance callaway engineers have changed the way the face reacts at impact to promote more ball speed during impact the face flexes and the crown bulges up and the sole bulges down wards the jail break bars which are three gram titanium bars that attach the crown to the sole to stiffen the body of the club and restrict this unwanted movement so more energy is transferred back to the ball for more efficiently an