Philips Respironics :
1082662 One of the keys to the SimplyGo Oxygen Concentrator's portability is the battery. SimplyGo batteries are lightweight (about 1.5 pounds each) and compact. When inserted in the machine are easily accessible and can be quickly changed by oxygen users on the go. Just slip out the old battery and slip in a new one to extend your time on the go with the SimplyGo.