Philips Respironics EverFlo Home Oxygen Concentrator 5 LPM with OPI CPAP Mask SIZING: Two headgear sizes are Size:Adult Arm Splint SIZING: Two headgear sizes are available: All Small Eson 2 masks come standard with Small Stitchless Headgear and 1 through 8 with 1 being the lowest level of humidification A recessed flow meter reduces the risk of accidental breakage and the metal cannula that it uses is more durable and less likely to break than other types very low oxygen: 70% Operating temperature 55°F to 90°F (12°C to 32°C) Storage transport humidity 30°F to 160°F ( 34°C to 71°C) up to 95% relative humidity Operating humidity Up to 95% relative humidity Outlet pressure 5