Features and Benefits:1" hex bit with internal 10mm hex bit designed to securely fit Subaru®hollow cam sprocket bolts;more stable and safer than others;impact-rated and black oxide finish;A great companion tool to the Cal-van 754 3-in-1;The cam sprocket bolts on Subaru®require more force than a 10mm Allen wrench is good for, and an impact bit doesn�t provide much stability. Use this bit with a 1" socket or wrench for better torque and can be used with impact tools to make it even easier.