Features: 1. EQUIPPED WITH CHIP AND CONTROLLER: The 4-channel Micro USB relay module features a stable USB to serial port chip and microcontroller. 2. SWITCH CONTROL: Serial commands can be sent from a computer using serial debugging software to control the opening and closing of the 4-channel relay. 3. EASY TO USE: Built-in HID control chip, driver-free, plug and play, convenient for you to use, useful and practical. 4. PROTECTION FUNCTION: The module has overcurrent protection and relay freewheeling protection, making it very safe. 5. LONG SERVICE LIFE: Built-in 5V, 10A 250VAC, 10A 30VDC relay, the relay's lifespan can be continuously engaged 100,000 times. Specification: Item Type: 4-channel relay module Material: PCB copper board. Package List: 1 x 4-channel relay module Note: You need to insert the device first and then open the software, as the software will only detect if a device is inserted and establish an automatic connection when you open the software.