Under chin seal provides for a more comfortable and stable fit 15 small vented holes at the bridge of the nose for quieter operation while minimizing dead space Dual swivel elbow aids patient movement Built in ports allow supplementary oxygen and pressure monitoring Free Motion Glider™ with quick release clip enables freedom of movement with single motion refit Anti-asphyxiation / non-rebreather valve included for safety in the event of flow source failure For use with single limb systems Available in three sizes; small; medium and large