The head is the most distinctive feature of the Boxer. The breed standard dictates that it must be in perfect proportion to the body and above all it must never be too light. The greatest value is to be placed on the muzzle being of correct form and in absolute proportion to the skull. The length of the muzzle to the whole of the head should be a ratio of 1:3. Folds are always present from the root of the nose running downwards on both sides of the muzzle, and the tip of the nose should lie somewhat higher than the root of the muzzle. In addition a Boxer should be slightly prognathous, i.e., the lower jaw should protrude beyond the upper jaw and bend slightly upwards in what is commonly called an underbite or 'undershot bite'.