Pro-Thread Kits offer a cost effective method of repairing and strengthening threads in various materials such as cast iron, steel, aluminum, and other metals and plastics; Effective for automotive repair, spark plug ports, outdoor power equipment, motorcycle repairs, farm equipment, and more!; Easy to install, just DRILL, TAP, INSERT, SNAP!; Pro-Thread inserts provide a permanent wear resistant internal thread; Stainless steel inserts resist the effects of temperature and corrosion; Wire inserts help to compensate for the thread and pitch angle errors; Repaired threads are generally stronger than the original parent material thread; Thread Size: Metric M12 x 1.25; Includes tap, installation tool and set of inserts; 2 x 1/2" , 2 x 3/4" OAL inserts