A gasoline powered device used to reduce brush and tree limbs to wood chips. This is done by applying the refuse to a large, toothed drum, spinning at a high speed. One brand, the Eager Beaver (I kid you not), uses a spinning disk instead; Cuisenart style. They are very satisfying machines to use and are right up there on the "God awful noise scale". Some people would use them to dispose of things other than landscaping refuse.