The OASYS appliance repositions the mandible to bring the base of the tongue forward, opening the oropharynx and strengthening the upper airway to increase the compliance and have greater resistance to airway collapse. It accomplishes dramatic nasal opening by means of the “nasal buttons” that extend off the upper shield that applies a stretch to the inner nasal structure from within the mouth, decreasing resistance to airflow through the nose by an average of 80%. The appliance is easily adjusted to situate the mandible in the most effective forward position.