The Lunati Gear Drive design significantly reduces timing movement through the RPM range. They are made from heat-treated billet steel for timing accuracy, durability and a 4° advance/retard can be achieved through either cam gear dowel pin inserts or three keyway crank gears. Made for street performance applications with a blower sound feature. Kits include dowel pin advance/retard inserts, a rollerized cam button for use with a roller cam and a lock plate with the bolts.