THE BISON 0643-10/6 IS A 4 JAW CHUCK WITH A D1-6 BACKPLATE MOUNT. ITS MEASURED DIMENSIONS INCLUDE AN OVERALL DIAMETER OF 10 INCHES AND A 2-1/2 INCH CENTER HOLE. THE CHUCK FEATURES 4 T-SLOTS AND IS EQUIPPED WITH 6 TOTAL PINS, EACH MEASURING 0.875 INCHES. THE OUTER CENTER HOLE DIAMETER IS 4 INCHES.