Rear Brake Rotor - Surron/Talaria 203mm x 1.8mm Size: Surron Light Bee are 203mm diameter Rotors from the factory. The 203mm Rotor does not need a caliper bracket and is a one piece 1.8mm thick rotor same as factory thickness. 220mm x 1.8mm Size: this is an upgraded oversized rotor that provides additional braking force. A perfect upgrade if you’re a hard rider and pushing the limits of your current 203mm rotors. 1.8mm thickness one piece design  This 220mm rotor you will need a caliper adapter bracket to space the brake caliper out for the bigger rotor.  The bracket for the rear brake can be found here. 220mm x 2.3mm Floating Size: this is a beast of a rotor and a serious upgrade that provides the best braking possible. A perfect upgrade if your running bigger/heavier wheels and insane power output 2.3mm 2 piece designs helps with heat cycling which is major reason rotors warp. The 2 piece design helps stop that from happening This 220mm rotor you will need a caliper adapter bracket to space the brake caliper out for the bigger rotor. The bracket for the rear brake can be found here.