Fortress Interlocks Ltd. is a world leader in the design and manufacture of safety interlocks for all industries. Fortress' amGard range is made up of robust gate switches and solenoid Interlocks designed for heavy duty applications. eGard's modular design allows configurations of purely safety gate switches, purely trapped key interlocks, purely machine control stations or any combination of the three. mGard is a completely modular approach to trapped key interlocking.