It's really only for one device, at the moment (Note 4), but I'd rather not have to charge the battery pack itself as much if I can help it. Thanks, I'll check that one out.
I have an battery packs by Anker, PowerAdd, and Ravpower. All are good. I also have a Note 4 that just got retired to the drawer. It got many charges from my PowerAdd 20,000 mah battery pack.