2-Channel Relay Module – 5V

There are 4 fixing screw holes around the board, the hole diameter is 3.1mm, easy to install And fixed 
The relay uses high quality relays, single pole and double throw. A common end, a normally open end, a normally closed end
Optocoupler isolation, good anti-interference 
Low level pull-in, high level release. The status indicator is on when the  inverter is closed, and the status indicator is off when released.
VCC is the system power supply, and JD_VCC is the relay power supply. The default is 5V relay, plug in the jumper cap. 
Relay maximum output: DC 30V/10A, AC 250V/10A
Size: 50.6mm x 38.8mm x 19.3mm