This purchase is for a pair of front axle sliders that help protect your bikes front fork in case of a low-side. It allows the fork to slide on the plastic puck instead of the fork itself. The installation is a simple bolt on with the bar going through the axle and one plastic puck on each side. The sliders are made of UHMW-PE (ultra high molecular weight polyethylene), a tough plastic with good strength, wear resistance and dimensional stability. It is more dimensionally stable than Nylon and used in many industrial ball bearing and friction reducing applications. The bolts are made of highest grade commercially available 12.9(177,000 psi in tensile strength). The long bar is made of billet aluminum. Rest assured that you are getting the best material commercially available.