The X5-D2 is designed for use with the Raptor in senior or junior classes. Features 2 friction discs for greater torque capacity than a one disc unit. Billet steel drum with bolt-on sprocket for truer running and eliminates power robbing distortion when kart goes through high speed corners. Billet drive hub with cooling vanes that increase surface area to absorb and transfer unwanted heat. Another first from Horstman is our patented 5x5 spring/lever combo for just the right amount of lock up and consistent performance. 2.850" disc size moves mass closer to crank centerline to reduce absorbed energy every time you get on the throttle.