This purchase is for a set of Frame Sliders for the above bike 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%. ÿThe slider puck is screwed on to the spacer. ÿThe 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 frame sliders since it can absorb more impact force onto itself and therefore reduce the impact on the frame and engine. 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.