Cast aluminum body. Billet aluminum driver arms. Steel left and right hand threaded adjustment screw with a knurled thumb wheel for maximum control. 3/16 broached hex in the end of the adjustment screw for another option to actuate the screw as well as assist in installing new driver arms. Arms adjust to install both 3" and 4" carrier nipples. Utilizes a 1/2" square drive for a ratchet or a cast square post which fits any 10" adjustable wrench. 100% USA made. Patent pending.