User interface device providing for improved cooling of the skin

A user interface element for delivering breathing gas to a user, comprising:

• a cushion defining an inner chamber for receiving the breathing gas, the cushion having an inner surface facing toward the inner chamber and an outer surface facing away from the inner chamber, wherein a portion of the outer surface is structured to sealingly engage a face of the user, and wherein three or more indentations are provided on the inner surface to form a varying surface texture such that the varying surface texture is structured to cause a turbulent gas flow over the inner surface;
• and
• a shell member coupled to the cushion, the shell member having a front end portion, a rear end portion located closer to the cushion than the front end portion, a central chamber, and a plurality of flow segment chambers surrounding the central chamber and extending from the rear end portion to the front end portion, the rear end portion having an inner edge and an outer edge spaced from the inner edge, the inner edge defining an opening of the central chamber, the front end portion having a first orifice for receiving a first flow of gas and a plurality of second orifices for letting a second flow of gas out of the user interface element, wherein each flow segment chamber includes a respective one of the second orifices and an inlet opening defined in part by a portion of the inner edge and a portion of the outer edge, wherein the first orifice and the second orifices are positioned relative to each other such that during use of the user interface element the second flow of gas:
• (i) flows over and cools a skin surface of the user and out of the user interface element through the one or more second orifices, and/or (ii) flushes at least 85% of any CO2 present in an interior of the user interface element from the user interface element through the one or more second orifices.