The Tusk heated grip kit is designed for ATVs and will not function with twist throttle. The Tusk thumb warmer is included, and works hand-in-hand with the Tusk heated grip kit. Tusk handlebar grip heater kit w/molded grips and digital control. Large injection-molded grips with built-in heat panels. Heat level is controlled by a digital switch that will let you choose five different heat settings, or turn them off entirely. Easy installation. Designed for ATVs with thumb throttles; will not work with twist grip throttles. Inner diameter 7/8". Compatible thumb warmer included.