Guard Interlock Switches are electromechanical or non-contact safety devices mounted to physical machine guards, access doors, and safety gates to monitor door position and prevent machine operation when guards are open. Available in mechanical key-actuated, magnetic, tongue-interlock, and RFID coded configurations, advanced variants feature solenoid power-to-lock mechanisms that keep safety doors locked until hazardous motion has completely ceased. Key hardware features typically include high-retention strength locking heads, tamper-resistant high-coded RFID actuators, heavy-duty metal or PBT polymer housings, manual unlock mechanisms, and dual-channel forced-opening safety contacts.