This is an industrial 8 channel relay module from Waveshare. It works over RS485 bus using Modbus RTU protocol. It has embedded protection circuits. It has power isolation, ADI magnetic isolation, TVS diode and more. It works with 5V, a 5V wall adapter is included as standard. There are 6 relays on the board that can switch ≤10A 250V AC or ≤10A 30V DC per channel. It is in an ABS case with support for rail mounting.