Adopt patch photocoupler isolation, strong driving ability, stable performance. Trigger current is 5mA. Module operating voltage options: 5V, 12V, 24V. Each path of the module can be triggered by high level or low level via jumper setting. Fault-tolerant design; even if the control line breaks, the relay will not activate. Power indicator light (green), 4-way relay state indicator light (red). Humanized interface design; all interfaces can be directly connected through terminal leads for easy use. Four fixing bolt holes provided. Specifications: Weight: 18g / 0.6oz Module Size (L*W*H): 50*26*18.5mm / 2*1*0.7inch Bolt Hole Diameter: 3.1mm; Spacing: 44.5*20.5mm Module Interface: - : Connect to power negative pole IN: High or low level control for relay activation Relay Output Terminals: NO: Normally open interface; before relay activates, it is open; after activation, connects to COM COM: Common terminal NC: Normally closed interface; before relay activates, connected to COM; after activation, disconnects from COM Trigger Selection Terminal: When jumper is connected to LOW, the module is triggered by low level When jumper is connected to HIGH, the module is triggered by high level Package List: 1 x Relay Module