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 the manufacturers claim they are intended for use with herbs and spices for cooking, they are often used to shred spices , and are often unsuitable for actual use with spices (which instead are prepared using a burr grinder), resulting in a product that can be more easily hand-rolled that burns more evenly. Herb grinders are typically made of either metal or plastic and come in a variety of colors and polished metals.
Some grinders have two or three compartments instead of just one, with fine screens separating the bottom compartments from the ones above, thus allowing the spice trichomes, also called kief, to be collected separately.