Fortress mGard trapped key interlocks mechanically safeguard dangerous machines and hazardous processes, and provide access control without the need for wiring. For electro-mechanical guarding, the Fortress amGard modular system can be configured to site specifications. With over 4 trillion possible combinations, the Fortress eGard line combines mechanical trapped key interlocks, electrical safety gate switch interlocks and electrical operator controls to form a completely custom system. 

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Fortress Interlocking; www.fortressinterlocks.com