An increment borer is like a hollow auger, extracting a small dowel-like piece from a tree that can tell a lot about tree growth, wood decay, or the penetration of preservatives in timbers. They are available with bits from 6 inches (like this one) to 2-1/2 feet long.
The red handle is hollow, and the drill bit and extractor can be stored inside the handle when not in use. the extractor is a long half moon shaped blade that slips inside the hollow auger and allows you to pull out (extract) the core sample. This allows you to look at the inside of the tree by examining a core sample. A review of the size of the growth rings will provide a lot of information about how the tree is doing. Data regarding age and rate of growth is critical in making forest management decisions.