VM4 is a mechanical interlock unit designed for the interlocking side-by-side without additional width of two 3-pole or 4-pole AF09...AF38, AFC09...AFC38, AFS09...AFS38 contactors. When mounted between two contactors, the VM4 mechanical interlock unit prevents one of the contactors from closing as long as the other contactor is closed. The mechanical interlock unit VM4 includes 2 fixing clips (BB4).