This relay module is 24V active low. It is a 4-channel relay interface board, which can be controlled directly by a wide range of micro-controllers such as Arduino,AVR,PIC,ARM,PLC etc. It is also able to control various appliances and other equipment with large current. Relay output maximum contact is AC250V 10A and DC30V 10A. Standard interface can be directly connected with micro-controllers. Red working status indicator lights are conductive for safe use. Widely used for all MCU control, industrial sector, PLC control, smart home control.