This is a special type of 380V plug. It has a built in feature which allows you to easily invert the phases. 2 phases are mounted on a swivel type of contact. All you need to do is unplug the device from power, then use a screw driver to rotate the swivel 180 degrees, and the phases are inverted. This plug is often used on construction sites, for sawing machines or other equipment where a correct rotation direction is essential. Some machine builders is it on their machines, so its easy to invert the phases, in case the on site installation is incorrectly phased.