This instrument is called a densiometer. We use this to figure out canopy coverage in one specific area and use it to know how much light is getting to the ground. We take what we find in that one specific area and apply it to a large area. To use this, you stand under a group of trees and hold it about 18 inches in front of you making sure that you use the bubble to level the instrument. You look at the instrument and count how many squares have canopy showing on them. When you get that data, you take the number of squares that had canopy coverage and multiply it by 1.04.