Evotech Performance has developed an innovated spindle/bobbin system which allows the bobbin head to rotate on impact. This is down to the aluminum spacer system that provides a solid core for the location of the nylon bobbin head. Using this system we have increased the overall durability and impact resistance of our bobbin kits. The spindle sliders/bobbins are retained by roll threaded stainless steel spindles for increased strength. The spindle slider/bobbin kits comprise of two nylon bobbins, two anodized aluminum spacers, stainless steel spindle, nuts, washers and a hollow spindle nut when required. Made from high performance engineering materials in order to protect related items in the event of a spill. Easy to follow online instructions to aid hassle free installation. Please note this item is for the double sided swing arm not the single sided.