Heli-Coil 5521-4 1/4-20 wire insert kit
Check compatibility
5521-4 is the Heli-Coil wire kit for 1/4-20. Buyers working on 1/4-28 need the corresponding fine-thread model.
Questions before ordering
Does this kit fit a 1/4-28 bolt?
Use Heli-Coil 5528-4 for the documented 1/4-28 repair size. The 5521-4 kit is the 20-TPI version.