An herb grinder (or simply, a grinder) is a cylindrical device with two halves (top and bottom) that separate and have sharp teeth or pegs aligned in such a way that when both halves are turned, material inside is shredded. Though intended for use with herbs and spices for cooking, they are often used to shred marijuana, resulting in a product that can be more easily hand-rolled into a "joint" that burns more evenly. Herb grinders are typically made of either metal or plastic and come in a variety of colors and polished metals.