AP Products Propane Tank Gas Level Indicator. Tank Checks unique Sensors accurately measure your Tanks LP level and communicate that information to you via the optional Monitor or through the use of most any device equipped with BlueTooth. The Sensors Blue Tooth communications range enables remote monitoring up to 50 away depending upon obstructions such as walls and other material. Features of AP Products Propane Tank Gas Level Indicator Save the hassle of constantly checking your LP tank level Monitor your tank level with LP Tank Check Follow manufacturer recommendations and guidelines to ensure proper usage Quick and easy installation setup LP Tank Check Dual Sensor Package Contents: AP Products Propane Tank Gas Level Indicator AP Products 024-1002: 024-1002 Propane Tank Gas Level Indicator