Comet 108 4-Pro clutches now accept OEM starter rings Added fourth load-bearing member increases roller and button life These race clutches are for high-performance applications ONLY Clutch uses four clutch weights to greatly enhance tuneability 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 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 Each features a new bushing in the movable face and redesigned fixed face for increased durability IMPORTANT NOTE: These clutches are for racing use only. For calibration contact a high performance specialist or Comet Industries.