The switch has the following functions, derived from power outage and undervoltage protection. Bipolar cut-off, unipolar cut-off function Both versions can be combined with overload protection switches for undervoltage and overload protection Widely used in machine tools, power tools, garden machinery and above. This is a safety switch. After the device is accidentally powered off, it will not turn on. You need to press the green start button to turn it on. Type: AC220V KJD17 4 Pin color:Black Material:plastic Package Contents: 1 x electromagnetic push button switch Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.