A useful set to mount a bobberseat / solo seat to your frame. You can place your seat springs over the pen (Ø12 mm). The set consists of two pins that you can weld to the frame or can bolt through the supplied stainless steel M8 Allen bolts with round head. They fit on a frame tube 1'' (Ø25,4 mm) but they are also easy to adjust to fit on a larger diameter tube. In addition, the rubber rings ensure that your paint is not damaged by the springs and the springs do not squeak. These chrome seatsprings are 3" (ca. 7.5 cm) high.