Grinder  (also called an “herb grinder” or “tobacco grinder”) is a cylindrical device designed to shred herbs, including cannabis. Devices are divided into chambers and layers that use metal or plastic teeth to shred through herbs. The shredded herbs are then collected in the next chamber. Although grinders have varying numbers of chambers, each grinder must have at least two chambers. Many grinders come with screens that serve to catch kief after it has been separated from the marijuana plant.