This is a 4-Channel 5V Relay interface board, able to control various appliances, and other equipment with current up to 10A.
It can be controlled directly by ESP8266
It can be set to either High or Low trigger
4 x High-current relay, AC 250V 10A ; DC 30V 10A
Optical coupling isolation
VCC system power, JD_VCC relay power, default 5V relay, just plug in jumper cap
Indication LED's for Relay output status
4 fixed screw holes, hole diameter: 3.1mm