For those who hate being stuck with one brand because the batteries are so expensive you can buy adapters to convert between them. For instance I use a rigid battery with a ryobi tool etc and it works great! I've seen adapters for working between most of the brands since almost all the tools are 18V. I've seen ones that jump between lower voltages and higher ones which is a bit sketchier but are likely fine as well. https://www.google.com/search?q=power+tool+battery+adapter