"This engine cylinder torque plate kit properly stresses the cylinder to stimulate engine operating conditions when boring and honing cylinders. Precision drilled for multiple applications, these plates have 4"" diameter hole to accomodate most large bores. Bolts are included for Shovelhead and Big Twin Evolutions. For use with Sportster Evolution, purchase bolt kit #F6554. For use on Big Twin Shovelhead and Evolutions and also Sportster Evolution Instructions included."