Product description the golfsmith cobalt steel pre reaming drill bit is perfect for re boring hosels on club heads made of notoriously difficult to drill metals such as 17 4ph titanium and marraiging steel this hss co alloyed and titanium nitrated drill bit holds its rigidity and hardness at higher temperatures better than a hss drill bit sized for enlarging hosel bores prior to reaming this drill bit provide a good epoxy bond allowance between shaft and hosel