Semi Auto with 17 teeth on the gear. Please make sure your clutch matches our picture and that the tooth count on your gear = 17 prior to ordering. Coolster 110cc ATVs: 3050B, 3050C, 3050D; Coolster 125cc ATVs: ATV-3125A2 ATV-3125B, ATV-3125C-2, ATV-3125CX-2, ATV-3125CX-3, ATV-3125R, ATV-3125X8, ATV-3125XR8,, ATV-3125XR8-S, ATV-3125XR8-U-S Tao Tao Models: ATA 125A, ATA 125D, ATA 125F1, Cheetah, TForce, Cheetah, T Force, ATA 135DU, ATA 135D This clutch may also fit additional models not listed above.