Just make sure you get Made in the USA batteries. Not sure if the imported batteries have gotten any better in the last 2-3yrs, but I have heard a lot of not so good things about the chinese ones. Shelf life can be iffy, some lack basic current and temp protections, some have have exploding issues, etc. Plus they aren't made here. If you want US made, Panasonic makes them for everyone (surefire streamlight and a couple others if I recall correctly). Get one of those 3 brands and you should be fine. Primary arms has good deals on the SL and SF branded batteries and if you search around you can find good deals on the Panasonic batteries as well. I usually wait for Primary Arms to throw the SF batteries on sale and buy a few things and a box or 2 of them. Usually works out pretty well that way.