Portable Oxygen Concentrator

My childhood friend who has acute asthma since she was 3 years old was recently diagnosed as suffering from acute pulmonary disease. When we met at a gathering recently, I was shocked to see her carrying a portable oxygen concentrator with her during the lunch at a hotel. It’s the first time I’ve seen a portable oxygen concentrator equipment but it wasn't as big or heavy as I've imagined. It only weighed 17lbs. She’s also under medication from her surgeon and I really hope she’ll recover in no time.