MICRO switch GKL/R series switches are a heavy-duty key operated solenoid safety interlock switch incorporating a key trapping mechanism. The trapped key attached to the guard cannot be removed from the switch until the solenoid circuit of the switch has received a remote signal (from a control device) indicating the hazardous process has subsided. This design is for use on machinery where an instant stop is either impossible (due to the momentum of the machine) or impractical due to machine conditions (such as completing a machine cycle or reducing the temperature to a safe level). There are independent contacts inside the key switch which monitor the key position and the solenoid with a range of different contact arrangements to satisfy most application requirements. All normally closed contacts of the switch are positive opening.