Herb grinder

The fine screen of a Space Case which will hold the larger pieces of herb. Also visible is the bottom compartment, where the trichomes will be collected.

Trichomes, or kief, collected below the screen of a grinder

Grinder for smokers

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 ostensibly intended for use with herbs and spices for cooking, they're more commonly 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.

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 marijuana trichomes, also called kief, to be collected separately.