A large problem with gas bottles is that it's almost an estimation when it comes to knowing how much you have left. Instead of shaking and guessing, try this new and ingenious way to see how much propane you have left in your tank. Designed to fit all BBQ and RV tanks, the Hammerhead Accu-Level Removable Propane Tank Gauge is the easiest way to measure propane levels. it's magnetic - so just attach to your tank and visually see the exact level of your tank. This Accu-Level Gauge is designed to withstand the Aussie sunlight; it won't fade and because of this, it lasts for years. For such an inexpensive solution to a frustrating problem, you'll get your money back from wasted propane in no time, when you have the Hammerhead Accu-Level Removable Propane Tank Gauge.