McGard “TUNER” security bolt set (4 bolts + 1 wrench).Tuner series is designed for rims with a small bolt hole. The outer diameter of the nuts/bolts and wrench in this series is smaller than that of the standard (SU) or UHS series (SL) bolts/nuts. Do not use a pneumatic wrench to tighten the security nuts! Each package comes with an ID number. You can order a spare chuck using this code!