My husband has an oxygen concentrator which he likes. It weighs 7 lbs. & is on a cart. He uses it just when he is in our home. He doesn't want the tank that he could carry around. He said the oxygen does not last very long & he would have to keep getting it filled. I wish he would get the tank. I see people at the stores with them all the time. We are confined to our house quite a lot because he just wants to use the concentrator. He has a bigger oxygen machine also which he likes & a nebulizer. What do you think of the tanks versus the concentrator?