This purchase is for a Rear Axle Slider. It provides indispensable protection for your beautiful expensive swing-arm. The slider pucks are made of 6061-T6 aluminum for strength, an aluminum that offers high-to-moderate strength, excellent corrosion resistance, and superior machinability and weldability. It is more dimensionally stable than Nylon and used in certain heavy duty structural applications such as truck frames, military and commercial bridges, aerospace applications, etc. The cross bar is made of 304 grade stainless steel for strength and rust-resistance. Rest assured that you are getting the best material commercially available. The sliders that you will receive will most likely be the ones pictured above. However, due to constant improvement, the sliders can sometimes vary slightly from those in the picture.