Review on Dottmon LED Battery Charger: Efficient Charging for Li-ion 10440-26700 Batteries by Maya Rico

The product does the job, but you need additional hardware to get the most out of it. Not sure if this is my specific device or how it's supposed to work, but only one slot works when charging via USB. I had to use the block charger that came with my phone to charge all the battery compartments. For $20 it's not that bad, but not worth it if you can charge your batteries in a vape, for example.