It is powered by built in batteries with ultra low power consumption. The batteries can be used for about one year to two years. It is applicable to most of the DVD navigation with direction control function on the market. This controller is universal, so you don't need to remove the steering wheel controller to work. It can support 5 buttons and 10 buttons two choices to meet the common operation needs of the car. Its super Touch-design, small space occupation and side button will not cause the wrong operation by steering the wheel. Integrated arc design is perfectly compatible with a of car steering wheels, without bad effect to the steering wheel cover. Being flexibly installed along the steering wheel as you like, this controller is easy to use and helpful to keep safety for your driving. Description: Item Type: Remote Controls Special Features: Easy installation and removal. Item Weight: 0.18kg Model Name: Controller Key Product name: Steering Wheel remote control Shape: Half Moon Controller Key Size (LxWxH ): about 10 x 4.4 x 3.5 cm/3.9inch x 1.7inch x 1.4inch Receiver Box Size (LxWxH ): about 4.3 x 3.7 x 1 cm/1.7inch x 1.45inch x 0.45inch Material:ABS colour:Black Package Contents: 2 x Controller Key (with built-in button battery) 1 x Receiver Box 1 x Wire harness 1 Set x Screws 1 x Instruction manual Only the above package content, other products are not included. Note: Light 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.