Material: The RC model car sound group is made of abs shell, metal electronics ,which is sturdy for long term use Compatibility: Remote control car sound is for 1/28 1/24 1/18 1/35 climbing car truck Easy to Install:This rc car part is easy to install tp replace old or broken part. Control Method: Once turned on, the engine sound will automatically start when throttle channel moves for the first time; if idle for over twenty seconds, it will automatically shut off but restarts upon throttle movement again. Note: Please note that the maximum supply voltage for the sound group is to no more than 5V. If your electronic speed controller's BEC is rated at 6V, it's recommended to connect two diodes in series from the to reduce voltage drop between approximately between1.2-1.4V. Specification: Output power: 1W 8 ohms 5V/0.6 ohms 3V input: positive 0.8 ms to 2.0 ms Sound quality: 22.05 kHz sampling frequency Memory: 4M, 22.05 kHz audio for about 20 seconds Size Chart: Package 8cmx12cmx1cm/3.15inchx4.72inchx0.39inch Package Includes: 1 RC Sound Group Note: Please allow slightly errors 1-2cm differences due to manual measurement.