Solves problems of a mechanical shifting related to a mid drive unit. gearsensor works similar as a clutch in the car. When the user starts with a shifting, the motor power is cutted off or reduced for a necessary period of time which is required for a smooth shifting. Provides perfect shifting in any situation (for all standard rear/front derailleurs and internal gear hubs). Prolongs lifetime of the whole shifting system. Removes loud sounds and decreases chance to break a chain during the shifting. Provides easy shifting as on a normal bicycle. Waterproof Plug Connector: 3Pin Male Length: 33cm(37cm including plug) Function: Cut off Power during gear shift to avoid grinding and cassette breaking, Extend life of the bike chain and cassette Compatibility: BBS01 BBS02 BBSHD Mid Drive Motor or other Brand Mid motor Kit Color:Black Material:plastic Package Contents: 1 * Shift Sensor Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.