This product can safely and accurately measure the capacity, according to the temperature test, measuring the temperature range of -10 C~ 120 C. Will actually show you when you are low on , you run out! Works while you are using the BBQ Save money by using more from each cylinder Safe & accurate Reusable Works on (propane) & butane cylinders Magnetic backing allows for easy reuse on exchange bottles Comes with instruction Instructions: 1.Place your Level Indicator on a clean area on the lower half of the cylinder. 2.Turn on the and wait 10 minutes 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. Colour:black Material:pet Package Contents: 3 x Magnetic Cylinder Tool Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.