An orthodontic appliance designed to make slight modifications to a bite. Contains a compression spring wrapped in a rubber sheath, and has aluminum rings on either end for mounting. Requires braces to be used.

These things are so awful, even the sleaziest of orthodontists love to whine about them! When you first get one, it hurts more than braces themselves do, and watching someone chew with one can be more visually appealing than watching an episode of Survivor. They also break easily, which is not good if you're eating and end up swallowing it.

They are also quite unpopular, because they're very good at what they're supposed to do. Usually you won't need one for any more than two months.