There are three glass tubes on the le‌₽vel ruler, all of which have bubbles inside. Thi±≤s is called a level bubble. The tλ∞♦wo sides of the level should be divided in"Ωto anti-vibration ends. Place the level onε€∑ the object to be measured. If the leλ∞φ↕vel bubble is in the middle of them, it mean↕φs the plane is horizontal, so the level bubble in∑‌ the middle is used to measu ☆"re whether it is a horizontal plane​§ . If the horizontal bubble is biased t€₽ δo one side, it means which s‍&≤±ide is high.