The ST 15 is a 5" 3 jaw chuck with two sets of jaws. It comes with mounting bolts and a key. Please note that the ST 15 is STANDARD equipment on all SHOPMASTER machines 2000-2014 and was standard on all SHOPTASK machines from 1990 to 1999. SHOPTASK and SHOPMASTER spindles are factory machined and ground to accept this chuck. CAUTION: Jaws are matched to the chuck body, so loss of a jaw will require the replacement of the entire chuck.