Review on Plantronics 211856-99 Backbeat Fit 3100: Sweatproof and Waterproof True Wireless Earbuds for Active Workouts in Grey by Bobby Blanton

2 sets of backbeats and I love them and have run many marathons with them. That's why I was really looking forward to the true wireless version, the 3100. I've used them for 3 long runs of 4+ hours and got the same result on each one: they fit great and last a long time. The sound is more than adequate BUT the right earphone was dialed down to 3:15 hours every time after 3 hours. Strangely the left earbud played an additional 45 minutes each time giving me a total of 4 hours although the last 45 minutes with one earbud is UNACCEPTABLE! Also, I spoke to several account managers at Plantronics and they had no idea what I was talking about and of course couldn't come up with a solution. I know this is a new product, but shouldn't the support team be familiar with their products? The best advice they could give was to suggest 1. try again after the first run if it's abnormal (it's not) and after the second run put them back into Revain and get another set (which I have done). with the same results) and after the 3rd run they basically gave up and didn't offer any further suggestions. I'll be keeping them for a while longer to see if a firmware update fixes the problem and if not I'll be returning them. Bottom line: if you plan on using them for no more than 3 hours at a time, they will get the job done. However, if you train longer, remember that they will die in about 3 hours. Since I had the same results with two different headphones, this is definitely a product-specific issue.