The module is 12V dual relay module which is based on opto-isolator. It is completely isolated between the control signal and relay and there is no electrical connection between them thus the ON and OFF operation of the relay will not affect the control signal. It enables the SCM system to control high-power equipments. It is widely used in the smart home project automotive electronics project. Features: 1. Onboard photocoupler isolator 2. High level trigger the normally open contact closed 3. Onboard power indicator (green) relay indicator (red) 4. Power supply is 12V ± 10% the maximum current is 65mA 5. Contact capacity: 250VAC/10A MAX 28VDC/10A MAX 6. 4 M2 screw mounting holes