Interesting, they show the dual nipples version as both nipples being separate outlets, one for each membrane piston... the single nipples version has double the flow rate over the twin nipple version, as each membrane piston shares the one common outlet port ... indeed it is a neat little air pump, probably used in COPD oxygen concentration medical devices... I can see that lasting longer than 100 hours, most likely the motor has brushes, which has a limited life span.