The first use (or replace the battery) need to matching frequency. Press and hold car select button, until remote indicator light starts flash. Turn on the car ,remote indicator light wll be off,indicating the successful connection with the car,release the button,now the remote control can be used. This product is suitable for specific children's riding toys, please ensure that the purchased parts have the same appearance and model as the parts. Please check if other functions of your car are working properly, such as motors and batteries. Specification: Material: Plastic Need 2 AAA Battery (Not Include) Size Chart: Controller 1: 150x105x50mm/6x4.1x2inch Controller 2: 150x100x60mm/6x3.9x2.3inch Controller 3: 155x52x23mm/6.1x2.1x0.9inch Receiver: 125X68X33mm/4.9x2.7x1.3inch Package Includes: As You Choose Note: Color might be slightly different due to the color calibration of each individual monitor. Please allow slightly measuring deviation due to manual measurement.