Longji GrillPro Magnetic Gas Level Indicator Gauge Caravan Bottle Propane But. Material: PET Plastic+ Liquid Crystal + Soft Magnetic This product can safely and accurately measure the gas capacity, according to the gas temperature test, measuring the temperature range of -10 C~ 120 C. Will actually show you when you are low on gas, before you run out! Works while you are using the BBQ Save money by using more gas from each cylinder Safe & accurate Reusable Works on LPG (propane) & butane cylinders Magnetic backing allows for easy reuse on exchange bottles Comes with instruction Never run out of Gas from now on. Measure your Gas with this level indicator, simply attach it to your gas tank cylinder with this magnetic Gas Level Indicator and it will show you how much gas is left in your tank. Instructions: 1.Place your Gas Level Indicator on a clean area on the lower half of the cylinder. 2.Turn on the gas and wait 10 minutes before you can read your Indicator. 3.In the winter the bar on the left will be active, and in the summer the bar on the right will be active. Buy with confidence.Any problems please feel free to leave messages to us. Will solved within 24 H (refund/replace/return.)