The purchase is for a set of engine guards for the above bike model. The engine guards feature UHMW-PE pucks that can be inexpensively replaced without purchasing a new set of steel guards. Think of it as protection for your protection. The steel tubing is bolted to the engine mount of the bike and the puck is bolted onto it. The steel tubing has three mounting points (each side) to prevent them from rotating in the event 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.