These bolt-on spring mounts can be mounted on a frame without having to weld. This kit contains the seat spring mounts, saddle washers, bolt and lock washer which are all black oxide coated so they blend in with your frame. This kit can be installed by drilling two 5/16 inch holes through your seat cross-tube and bolting them in place with the included hardware. In addition to a very easy install, if you decide to change your seat style in the future it is much easier to unbolt these mounts and fill in the holes versus cutting welded mounts off of your frame. The hex head bolt and saddle washer keep a vintage style that looks great with custom bikes of all types. This kit is designed to mate perfectly with 1 inch diameter frame tubing. Another high-quality kit from Lowbrow Customs, made in Ohio, USA.