Feature: External speed sensor hall for controller of electric bike, scooter and so on. The magnetic head is made of quality material, anti-rust, corrosion-resistant, durable. Easy to install, just clip the magnetic head to the spoke, and when wheel runs the magnetic head would work to transfer signal to sensor. It is used to provide sampling signal for LCD/LED display of electric bike, so that display can test bike speed. Nice accessory for DIY your own electric bike or scooter. Spec: Material: Plastic Color: Black Cable Length: Approx. 186cm / 73.22inch Magnetic Head Size: Approx. 1.6 x 1.2cm / 0.63 x 0.47inch Weight: Approx. 48g Package Included: 1 x External Speed Sensor 1 x Magnetic Sensor Notice: Black cord is for ground electrode, red for 5V power, green for Hall signal.