Limit switches serve as the mechanism that tells the computer the limits of the CNC machine. When one of the axes moves to an axis limit, the switch is activated and the machine stops. These limit switches are also use to inform the computer of the home position. Typically, 6 of these switches are needed, two per axis. This particular limit switch is rated for 125/250 volts AC (VAC) and can handle 15 amps of current. For limit switch use for CNC machines, it will be connected to signal voltage levels like 5v, but you have the option of using this switch to turn on/off a device that has mains voltage levels (i.e. using it as an interlock to turn off something when a door is opened).Click here for more information on this product.See instructions for this product.