Abstract: An oral device for improving the breathing of a user by means of protrusion of the lower jaw includes a first dental rail that covers at least some teeth of a lower row of teeth of the user; a second dental rail that covers at least some teeth of an upper row of teeth of the user; and at least one coupling element connecting the first and the second dental rail. The first dental rail comprises a front, labial connection point and the second dental rail has two rear, buccal connection points positioned substantially at its two posterior ends. The coupling element has a substantially U-shaped configuration, and an apex of the coupling element forms a joint with the front labial connection point on the first dental rail. The posterior ends of the coupling element form a joint with the rear connection points of the second dental rail.