Most people by this for their cell phones. I bought it for my Garmin Edge GPS and it works great! The GPS uses a USB charging port so it was a direct fit and charge.One reviewer mentioned it didn't take rechargeable batteries. I put Energizer rechargeables in and they fit and worked fine. No modifications needed.The changes I'd recommend: 1) do something about the short and easily loseable adapter cables, 2) change the location of the battery diagrams from inside the case to outside, they're hard to read on the inside.