This purchase is for a pair of engine case cover sliders and a stator cover slider (one LHS and one RHS). That helps protect your bikes engine case and stator Cover in the event of a low-side. The slider pucks 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. They can be inexpensively replaced in case of a low-side. The bolts are made of highest grade commercially available 12.9(177,000 psi in tensile strength). Rest assured that you are getting the best material and fully thought out product.