Feature:Module Size: 73*50*18.5mmWith 4 fixed bolt holes, diameter 3.1mm, spacing 44.5*67mmHigh and low level trigger selection:Trigger current is 2-4mA, trigger low level is 0-4V, trigger high level is 4.5-12V 1. S1 1 way relay high or low level trigger selection;2. S2 2 way relay high or low level trigger selection;3. com and low in short circuit, the relay is low level trigger, com and high end