Vacuum gauge

A vacuum gauge is a special tool that helps people measure how much air or gas is inside something that is sealed, like a jar or a container. It tells you if there's a lot of air or gas inside, or not very much at all. It works by using a small piece of metal or plastic that moves when air or gas pushes against it. The movement of this piece is then shown on a little dial, so you can read how much air or gas is inside the container. It's like a little helper that tells you if the container is full or empty, which can be very helpful in certain situations, like when you're working with machines that need a certain amount of air or gas.