These products are used for reinforcing female threads. These can be used with damaged female threads or soft materials to enable screws/bolts to be tightened. In general, coil inserts that have been machined into a coil shape are very common, but we also have a wide lineup that includes "self-tapping inserts", "inserts for resin", "insert nuts", "locking inserts", etc., enabling use to suit various environments or materials. MISUMI enables spec searches and ordering quantities from just 1 piece. Tools are also sold in addition to the inserts themselves. [Materials] Iron, stainless steel, brass, phosphor bronze, Inconel, nitronics [Size] M1.4 to M39 are available as well as imperial sizes [Search Keywords] Heli-Sert, E-Sert, Sprue, Female Thread