Why is the surface of the handheld sprayer calibrated

When we buy the products of the hand-held sprayer manufacturer, we will find that the surface of the hand-held sprayer is marked with some scales. Why?

With the development of modern society, the use of any product requires a certain amount, especially for the use of liquids, so that it can be well used when it is used, because the hand-held sprayer is mainly spray liquid, Different plants require different amounts of water or liquid, so the scale becomes very important. Otherwise, using more will hurt the plant, use less and not achieve the effect we want, so we need scale as a measure.

The importance of the scale is still very large, because the range of use of the hand-held sprayer is very wide, especially when it is necessary to spray the liquid.