1~10PCS Gas Level Indicator Propane Butane LPG Fuel Gas Tank Level Indicator Bottle Temperature Measuring Stick Magnetic Material: PET Plastic+ Liquid Crystal + Soft Magnetic Size: 10*6.2cm*0.1cm/3.94"*2.44"*0.04" : Black Quantity:1Pc 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 on the left will be active, and in the summer the on the right will be active. Specifications: 1This 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! 2Save money by using more gas from each cylinder 3Safe & Accurate & Reusable 4Works on LPG (propane) & butane cylinders 5Magnetic backing allows for easy reuse on exchange bottles Package Included: 1* Gas Level Indicator