Disclosed is a mandibular advancement device including a first frame, a second frame, a first rib on the first frame, the first rib extending generally from a front side of the first frame to a back side of the first frame, a first upstanding sidewall facing the first rib, a first channel on the second frame, the first channel in relative position to interface with the first rib, and an opening of the first channel, the opening of the first channel having a width that is narrower than a width of the first rib.
