Sonoff 4CH Pro - Whats on Boards?

You may choose to power up by 5-24V DC or by 90-250V AC. Each relay
without voltage output.
R1-R4 work as local control switches, you can directly press it to turn
on/off the corresponding gang. They also work as pairing button.
If you connect the Sonoff 4CH Pro with a motor, the wiring instruction is
as below: