MillerTech Falcon 7" Turbo Fan Powered By 18V/20V Power Tool Batteries

This is a great fan if you have a bunch of batteries laying around

Puts out good airflow with minimal power required. Fits my Dewalt batteries like a glove. Variable speed via a knob, which I like over typical pre-set speed settings (i.e., "Low / Medium / High"). Quiet operation, compact when not in use -- there is a LOT to like about this fan. So much so, I bought 2 of them!