I had the Inogen G5 when I was on oxygen. It worked well and was relatively quiet. You did have to worry about it overheating in the summer though if it wasn't getting enough ventilation. When it overheats, it sounds an alarm and shuts off. The Inogen G5 would go up to 6 liters, which proved not to be enough for me later on. If you renting, it may not be as important, but you might want to make sure of what level it will go up to.