It is used for attaching / detaching a special wheel bolt with a small hole diameter and deep. The outside diameter is thinner than the other wheel made exclusive products etc, and the thick part can be shortened by using the extension, so the risk of scratching the painted surface around the hole has been reduced.
Bolts that are stuck and need to be turned with high torque inevitably have a very high chance of licking the corners of the bolts. At such time, KTC 's Nepros has a very good fit and can be used with confidence without licking. I definitely would like to recommend it to everyone.