The Vaporesso XROS 3 Nano is the smaller, lighter version of the XROS 3, made for people who want the same easy mouth-to-lung vape in a more pocketable shape. It takes XROS pods, so you're in the same widely available pod family, and refilling and swapping pods is as simple as it gets. The trade for the smaller size is a smaller battery, so you'll charge it a bit more often than the full XROS 3, but it tops up quickly. There's adjustable airflow to set the draw tighter or looser. It's a sensible choice if portability matters most to you, or as a second device to keep on you, and you don't mind charging more frequently for the smaller footprint.