Precision machined 6061 aluminum for tighter tolerances than stock cast adapters, minimizing pad/rotor alignment issues and pad rubbing 4 Bolt Design utilizes four equal-length titanium bolts eliminating the need for cup/cone washers and providing an easier installation experience Choose from four adapter sizes (+20mm, +23mm, +40mm, +43mm) Kit includes (1) adapter, (4) titanium black bolts and washers Made in USA