Gas Level Indicator for Liquefied Gas Cylinders Visual gas level indicator that shows how much liquefied gas remains in your cylinder, helping you avoid running out unexpectedly. Gas residue test card uses PET and liquid crystal material to produce color changes based on the pressure and temperature of the liquid and gas inside the tank, providing a clear margin reminder. Simple usage: place the test card at the bottom of the tank and slide it upward slowly. The card will display a color change; the position where the color changes corresponds to the remaining amount of liquefied gas in the cylinder. Magnetic attachment: easily attach to your gas cylinder with the builtin magnetic mount for quick reference without tools. No power required and easy to read at a glance. Compact and lightweight for convenient use. Specifications and features Function: gas level indicator for liquefied gas cylinders Material: PET plus liquid crystal compound Attachment: magnetic mount for simple application to the cylinder Coverage: provides a visual indication of remaining liquefied gas based on internal tank conditions 23 practical use scenarios Home kitchen or domestic cooking: check the cylinder before starting a long meal to ensure you won't run out midpreparation. Outdoor grilling or camping: monitor gas level during preparation and cooking to plan a timely refill or replacement. Small workshops or maintenance tasks: keep operations continuous by confirming gas supply levels during extended use.