If you need to install inserts, the HELI-COIL 7551-04 Prewinder is an essential tool. It allows you to easily and quickly insert the thread inserts into the threaded holes. The prewinder can be used with a 4-40 size internal thread. Made of steel, this high quality tool has a durable construction that will stand up to repeated use. The HELI-COIL Thread Insert Tool is a great investment for your workshop.. This item has been restricted from sale in the following state (s): []