Portable Oxygen Concentrator Main Features: 3 million negative ions purify, 5 layers of filtration purify oxygen, let you breathe fresh oxygen. The oxygen generator is only 3.5kg, which is very convenient to carry. It can meet the requirements of all kinds of people. Not only does it make a great gift for parents and expecting mothers, but it can also provide oxygen for your car. Portable oxygen concentrators can not only be used at home, but also favored by people who like to hike and travel.