MEUS Racing RC Car Speaker MS-24 Engine Sound Simulator for 1/18 TRX4M, 1/24 SCX24 FMS, and other Vehicles. Key Features: 1. Supports up to 10 built-in engine sounds and 5 built-in whistle sounds, and can switch freely between different engines and whistles. 2. Supports arbitrary switching between engine mode and Bluetooth mode, and can be quickly switched by CH3 or buttons. 3. Adopts SGS (Sound Particle Synthesis Technology) and SFC (Intelligent State Following Compensation Technology) to make the sound more realistic. 4. Supports voice operation prompts and easily sets the engine sound, whistle sound, deflation valve sound, brake sound, and throttle forward and reverse. 5. Product size: 40*30.5*22MM, supports 2-3S power supply. Suitable for 1/12, 1/18, 1/24, and other models. MS-24 Engine Sound Simulator Manual Note: this RC speaker doesn't work with the stock electronics on the TRX4M. Because the original ECS does not have a CH1 interface. The speaker requires separate CH2 and CH3 interfaces. If you wish to use it, you will need to replace the Transmitter and ESC electronic components. Specifications: Material: Plastic Size: 40*30.5*22MM Weight: 34g Input Voltage: 6-12V Speaker Power: Rated 3W, Max. 4W Package List: 1 × RC Car Speaker Engine Sound Simulator