Huina 350 550, Huina remote control and receiver. This 15-channel system can control 6 small motors forward and reverse. The remote control requires 2 x 1.5V standard batteries (not included), with a maximum voltage of 3V. Receiver motherboard voltage: 7.2V (small power board). When input voltage is 7.2V, the output voltage for each motor group is approximately 5.4V. Remote frequency: 2.4GHz signal for stable performance and extended control distance. Regarding 2.4GHz frequency remote control: In theory, the 2.4GHz band supports up to 400 frequencies, allowing multiple users to operate simultaneously without interference. For example, if two or more 2.4GHz frequency toy cars are used nearby, they will not interfere with each other. This level of non-interference is not possible with low-frequency remote controls. Therefore, the 2.4GHz system requires frequency pairing before first use. Even in environments with multiple 2.4GHz devices, interference will not occur once properly paired. Frequency pairing method: Turn on both the remote control switch and the receiver board simultaneously, or turn on the receiver board first, then immediately turn on the remote control within 1–5 seconds. At this point, the indicator light on the remote will begin flashing, indicating automatic frequency synchronization. Once the flashing stops, the pairing process is complete—typically within 10 seconds. After completion, the system is ready for use. Pressing the respective buttons will control the corresponding motor direction. Wiring instructions: Power supply must provide DC voltage between 6V and 7.2V. Ensure correct polarity when connecting power; reversed polarity may damage the unit. Color: yellow. Material: plastic. Size: 8.9 cm x 4.5 cm. Package Contents: 1 x Remote Control (batteries not included) 1 x Receiver Board with Speaker 1 x Screwdriver (packaged in zipper closure bag) Only the items listed above are included. Other products are not included. Note: Lighting conditions and display settings may cause slight variations in color between the image and the actual item. Measurement tolerance is +/- 1–3 cm.