THIS ITEM IS A BISON 3 JAW CHUCK DESIGNED FOR LATHE OPERATIONS. IT FEATURES A 12-INCH DIAMETER AND INCLUDES A D1-8 BACKPLATE FOR MOUNTING. THE CHUCK'S MEASURED DIMENSIONS ARE APPROXIMATELY 4-5/8 INCHES IN HEIGHT (NOT INCLUDING THE JAWS AND BACKPLATE), OR APPROXIMATELY 9 INCHES WITH THE ATTACHED JAWS. IT HAS A HUB/CENTER HOLE SIZE OF 4 INCHES. THE D1-8 BACKPLATE INCLUDES 6 PINS, EACH 1 INCH IN DIAMETER. THE PIECE IS EQUIPPED WITH 3 JAWS ATTACHED.