RadBeacon Dot

Measuring in with a 1 1/8" diameter, this beacon broadcasts a Low-Energy Bluetooth signal that smartphones can detect for a few dozen meters.  This is the kind of technology that requires imagination to put to use.  So perhaps you would put one in every hospital room and your medical app could keep track of where all your doctors and nurses are located.  Any use where knowing your location is useful, particularly indoors where GPS is useless, could be a winner.

https://www.amazon.com/gp/product/B00JJ4P864