Some companies that sell propane tank level gauges include Creative Electronic Products Inc., Most Capable Engineering and Harbor Freight Tools. The site for these companies are PropaneGasGenie.com, MosCapEng.com, and HarborFreight.Com respectively.
For Creative Electronic Products Inc, the product goes by the name Propane GasGenie® and is available at both the company website and Amazon.com. GasCheck from Most Capable Engineering uses ultrasound technology to determine the level of propane. For the gauge to give correct measurements, the user must place it at a perpendicular angle. In addition, the surface of the tank should be clean. For Harbor Freight Tools, the brand name of the device is Smart BBQ. Smart BBQ is easy to use and applicable for many appliances.