“fits a wide variety of pro and unpro 18650s”
I like them a lot, the USB charging is very accurate, and the cell is Protected, which is important to me in case I fall asleep with the light on 
https://www.amazon.com/ARB-L18-2600U-rechargeable-charging-batteries-Edisonbright/dp/B01N2KKJXN
Protected, no charger needed, and does not make the flashlight useless while charging. Win Win Win