Features A Touch operate multi-functional units. 5Liter with 93%±3% oxygen purity output for COPD users Oxygen Purity Display by Numbers ( Accuracy 00.0%) Timer Large 6' LED Light Display all functional data Accumulated total running hours Special features only provided by AngelBiss Technology 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 3 years warranty or 18000hours lifetime Durable use for environment areas at high temperature (45C), high altitude (4500m). Accessories