This is the Hakko FX-901 portable soldering iron (available on Amazon: http://amzn.to/2sh7g0t). It runs off 4 AA batteries that you can swap out really fast with this removable cartridge design. I use rechargeables in mine and I get over an hour of use out of it before I notice the temperature drops. Alkaline batteries will run hotter, but not last as long.