I have used this concentrator for a few years now for travel. It is an outstanding machine -- built like a tank, reliable, and very consistent O2 output. I trust it because it is so well built and able to take the abuse that traveling places on it (I have drug the thing through city streets, around Disneyland/Disney World, on cobblestone sidewalks, and even on short hiking trails. I like things that are well built, and this is certainly a well-built machine. - Jeffrey