The Space Case titanium medium four piece grinder is the ultimate grinding machine. This four piece herb grinder is 2.5" in diameter and can grind anything you throw at it. The diamond-shaped sharp cut grinding teeth will never dull, and will be grinding for years to come. The top compartment is where you place the product and grind it up. From there it falls down into the lower compartment onto a screen. Any residue that comes through the screen will be collected in the bottom for convenient access.