Here the upper BioRest TM splint is locked into the BioPAP frame. The elbow and air valve can be removed just like in this photo. The lower splint locks in against anterior surface of the upper splint. This mechanism allows the user to open the jaw at wake periods, but during sleep it would remain naturally locked.
When upper and lower splints are in closed position the BioPAP framework seals the anterior marginal surface preventing air leaks through the lips.