Comet 108 4-Pro clutches accept OEM starter rings. Added fourth load-bearing member increases roller and button life. These race clutches are for high-performance applications ONLY. Uses four clutch weights to greatly enhance tuneability. Arms can be used in sets of two to better zero-in on desired weight. Uses same springs as 102-C and 108-EXP clutches. Captivated tower allows shouldered cover bolts to virtually eliminate tower spreading. Features a bushing in the movable face. To determine arm, add weight of three arms used in 108-EXP, add 14%, then divide by four; this will be the new arm weight to use. For calibrations contact a high performance specialist.