If I didn't have so many regular eGo batteries, I'd order a couple of the mega ones in a minute. I figure they will die one of these days and then I'll order the mega. Until then, I'll probably just keep going with these. At the rate I'm going, it will probably be a year from now. I tend to use my SB a lot more than my eGo anymore. I'm not sure, it could be about half and half, but it's making the eGo batteries last a longer, I'm sure. They're all over 6 months old now.