The Mountain High flare tip cannula is more suitable for pilots with larger nostrils, for users who experience trouble triggering the EDS unit, or for pilots who find that they need more oxygen than is supplied with the standard cannula.
The flare-tip acts like a gasket, taking up some of the room between the cannula and the nostril. The ability of the EDS unit to sense the drop in pressure during inhalation is thereby increased.
You must carry oxygen if you intend to fly at or above 10,000 ft. AMSL.
A cannula like this will come standard in an EDS kit, but it is always useful to have a spare if you may be sharing your oxygen kit or flying for many days in a row.