With a burr grinder, coffee is ground through pressure as it passes between two surfaces or burrs.

Flat burrs are made up of two rings that lie flat on each other. They are often horizontally aligned and have angled teeth. It is the distance between the rings that determines the size，in this design, the coffee makes two 90-degree turns. Because of their shape, flat burrs typically do retain more grounds than canonical ones.

Flat burr grinders supposedly meld and enhance darker notes, such as the nutty and chocolaty flavors of South and Central America.