Our sensors are design to use Bluetooth Low Energy or a propriety mesh network for longer range applications.  The standard sensors use Bluetooth Low Energy and the line of sight range with no obstructions is rated at 325 feet.  Generally speaking though, the sensors will work well throughout an average-sized home, or in the same or perhaps adjacent room.  We recommend testing by monitoring the Signal strength using the Smartphone app and a bit of trial and error can be necessary with obstructions in place, particularly if there is also a substantial distance involved, often the signal strength and connection reliability can be very dependent upon small changes in placement.  For larger spaces, we suggest using multiple gateways  our upgrade to our Mesh solution.