This application requires a special bluetooth device. More info about the TankCheck Sensor can be found here: http://mopeka.com/ This application is designed to be used with the Mopeka TankCheck sensor. The Tank Check application can measure the LPG propane level to tell you the exact fill level and when your tank is empty. It can be used on tanks found in RVs, heaters, BBQ grills, etc. The Tank Check sensors are magnetically stuck to the bottom of your propane tank and will periodically