9/16-18 Split Die Thread Chaser Repairs damaged fasteners faster than conventional thread repair tools. Eliminates the need for replacement parts that are often too long, too short, or the wrong hardness. Built for industrial use and made to withstand the conditions faced by the U.S. Military. Heat-treated, hardened, high-grade carbon steel (RC 58-60) meets the highest quality standards. By using a deep well six-point socket wrench, you can use our repair tool in tight quarters.