HiLetgo 2pcs DC 12V 2 Channel Relay Module With Isolated Optocoupler High and Low Level H/L Level Trigger Module for Arduino Can set high or low level trigger with jumper, to meet the demand of more trigger applications; With patch optical isolation, strong drive ability and stable performance; The module can be high or low by a jumper setting trigger; Interface design humane, all interfaces can be connected directly via terminal wiring leads , very convenient ; Fault-tolerant design , even if the control line is broken , the relay will not operate ;