GRAVITY Key Tether (Never Risk Losing Master Keys Again!) GRAVITY is the first and only industrial-grade, digital tethering solution that automatically preempts master key separation and loss - with absolute reliability. Now you can rest assured of never having to experience a card/key loss event and its costly aftermath. GRAVITY doesnt find access cards/keys, because they are never lost in the first place. GRAVITYs sleek, rugged design is engineered for workers daily use and convenience: 1) a handy key FOB holds the key ring and 2) a host unit that securely attaches to the users belt. The FOB is easily removed by pressing on the thumb release button and returned to the belt unit with a simple click and snap. GRAVITY tethers your keys while using an electronic signal that works as a 5-7 step, mobile barrier around the worker. Upon breaching this radius, GRAVITYs unique alarm, vibration and strobe light are triggered.