The KTT15S1SQ is a steel square soft lathe chuck jaw with 3 jaws, suitable for chucks with a capacity of 15 to 18 inches. It features a 1.5MM X 60° serrated attachment and a 1.6929 inch BTW mount hole centers. Measuring 6-1/2 inches long, 2-1/2 inches wide, and 4 inches high, this jaw offers reliable and precise gripping for your lathe chuck. It has a 0.8661 inch groove and a 0.7874 inch & 20mm fastener for secure fastening.