Portable Oxygen Bar with Turbo Air Flow for Travel & Home Use Due to the nature of the products. All sales are fine. Please read description below before purchasing Concentration: 29% +/- 2% (standard atmospheric pressure) Power Consumption: average below 32W / Rated Voltage: AC 100-240V / 50-60HZ or DC 12-15V Airflow outlet: approx 3 +/- 1.5L/min (standard atmospheric pressure) Battery Duration: 50-70 minutes per full charge