Yes, I have seen it. It is an eGo battery with the 3 or 5 click for 4.2v, 3.7v or 3.3v. If it went higher than 4.2v and it can't stay there very long due to the capacity, it would be a good unit. Not that it isn't now, but my customers want 5v-5.5v. And I think you have found that out.
I have tried talking to manufacturers to get them to produce a 5v unit, but they keep going back to the eGo.
Don