Congratulations on making the wise decision to run Formula brakes on your machine. Once you"ve chosen your rotor size, pick up one of these Formula Adapter Kits to match your brake mount type to your rotor size.Post Mount 6" 203 is for Post Mount brake mounts and 203mm rotors.Post Mount 6" 180 is for Post Mount brake mounts and 180mm rotors. Post Mount 7" 203 is for Post Mount brake mounts and 203mm rotors. Rear IS 203is for rear International Standard disc brake mounts and 203mm rotors. Rear IS 160 is for rear International Standard disc brake mounts and 160mm rotors. Rear IS 180 is for rear International Standard disc brake mounts and 180mm rotors