The Original Grill Gauge Propane Measuring Device Is A Must for Every Gas (Propane) Grill Owner. Never Run Empty Again! THE GRILL GAUGE accurately measures the propane in your tank. No batteries or power source is required. Simply attach the Grill Gauge to your propane tank to get an instant and accurate reading of how much propane is in your tank. Easy to use, dependable and durable, the Grill Gauge will never leave you guessing! No batteries required - No pressure needed - Doesn't matter what the temperature is - No hot or cold water needed - Works instantly! Portable, take it to the propane retailer to check your next tank before you buy.