aTurta Raspberry Pi 4 Relay Board is s 4 channel realy board allows you to control high power components via Raspberry Pi 2 and 3. The relays are isolated in the PCB. All the channels can control up to 30V DC or 220V AC on 10 A. You will find blue LEDs indicates the status of the relays. Relay pins are connected to the I/O 21, 22, 23 and 24 pins. Additional connections can be found on headers for 3.3V, 5V, GND, I2C, USART, SPI and 6 GPIO.