Bolt-in; for increased torque and horsepower. Camshaft & gear kit includes camshaft; drive gear and driven gear on camshaft. Includes all required bearings; o-rings and hardware. Gear drive cams provide improved valve timing accuracy and more mechanical sound; when compared to chain driven cams. Note: For best performance it is; like with all performance cams; recommended to use a free breathing air cleaner and exhaust system. Note: With each cam change S&S recommends their 583903 Precision tappet assembly set. Note: See the printed or online Motorcycle Storehouse catalog for the S&S camshaft specification chart.