This simple device takes the guesswork out of determining the level of propane gas remaining in a tank. A special thermochromic ink changes from yellow to orange when you pour water down the length of the gauge. Within a few seconds, the portion of the gauge that returns to yellow indicates the level of propane.
Apply one magnetic gauge for a 20 lb tank and two for a 40 lb tank. Initially immersing or pouring hot water over the magnetic tape will help flatten any kinks that have resulted from being packaged, allowing it to sit flat on the surface of the tank. Automatically resets within 30 seconds and can be reused indefinitely. (Avoid sharply bending the magnetic tape, as it may crack.) Made in USA.