This amazing tappet has broken the barriers of previous tappet designs. It performs like a hydraulic tappet from 0 to about 5.500 rpm at this RPM it becomes a solid, adding about 3 to 6 more useable horsepower. Another important feature is that Hydrosolid tappets have a built-in anti pump device. Available for Evolution Big Twins 1984 thru 1999, Twin Cam 1999 to present, and Evolution Sportster and Buells 1986 to present. For 1999 to present Twin Cam, and 2000 to present Sportster and Buell models there are also Special Application Hydrosolid tappets available. These are 1/4" longer, for high lift cams ground on a small base circle. Because of the limited space in the Twin Cam case, the travel is limited for high lift cams, but by using a performance high lift cam ground on a small base circle more travel of the tappet is achieved. A .700" valve lift is possible. Special application tappets are designed to be installed by the most advanced engine builder as modifications must be made to tappet covers. All Hydrosolid tappets are sold individually and must be used with adjustable pushrods.