ANGELBISS, The first one to make out the world's first battery operated 5LPM Oxygen Concentrator. Even produce 93% purity O2� at 5L/min flow. Features Durable Lithium Battery Operated DC 24V Fast recharge in 120 minutes, Continuous run 120 minutes (2 hours) 5Liter with 93%�±3% oxygen purity output for COPD users Oxygen Purity Display by Numbers (Accuracy 00.0%) Timer &� Touch operated buttons Large 6' LED Light Display all functional data Accumulated total running hours Special features only provided by AngelBiss Technology� The world's first battery operated 5LPM@93% Oxygen Concentrator The world's NO. 1� Oxygen Output Purity Fluctuation rate controlled within 0.1%.� Automatic heavy humidity remove molecular sieve Independent Oxygen outlet &� nebulizer outlet system Child Lock settings