This purchase is for a pair of luggage guards for the above models. The sliders feature a new design of a complete solid puck without a hollowed-out center. This increases the strength and contact surface to about 30%. The steel tubing is bolted to the sub frame of the bike and the slider puck is bolted onto it. The steel tubing has two attachment points preventing them from rotating in the event of a low side. The material of the puck is 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. Compared to Delrin, it is softer but tougher. Delrin is harder but more brittle. It is an ideal material for luggage guards since it can absorb more impact force onto itself and therefore reduce the impact on the bike. The slider pucks can be inexpensively replaced in case of a low-side. We use highest grade commercially available 12.9(177,000 psi in tensile strength) wherever possible. Rest assured that you are getting the best material commercially available.