Robomower STC 85161 Designed to work with the Robomower RM400 and Robomower RM200 models the Perimeter Switch is for activating extra plots or non docking plots, The perimeter switch comes with its own mounting stake and it is designed to work for 12 hours from being turned ON and then automatically shut off, Perfect for the convenience of having a switch for each zone rather than moving it from zone to zone, SKU: ST077