Important note:This product is suitable for use on bicycles with a wheel diameter of less than 36mm.This item does not include batteries or chargers.This is our newest electric regular bike kit that mounts the sprocket on the spokes so it fits most bike wheels.The motor uses a flywheel, so when the wheel spins, the motor doesn't spin, like a normal bike, which reduces drag.Thumb kit includes:1. 1x 250w 24v brushed motor with flywheel2. 1x chain3. 1x custom sprockets and components4. 1x Motor Controller5. 1x Mounting Plate + Bolt6. 1x Five Star Thumb Throttle (with battery indicator and switch button)Note: During installation, the two transmission wheels need to be adjusted to a straight line. The deviation of flywheel angle will tilt the flywheel stress point to one side, causing flywheel damage. The flywheel angle is generally adjusted through the mounting bracket of the motor.