This is a fresh-air respirator. It's a hobbyist thing. I don't think you'd find any professional giving this a thumbs up. But for the hobbyist, it's a great tool.
Essentially, you place the fan far away from where you are working. It draws in fresh air and pumps it through a corrugated hose to a mask. The idea is, you breathe air that it outside of the area you are painting, thus avoiding exposure.
This one is made by Breathe-cool. I've had it for about 10 years. I had a HobbyAire version before that but sold it when I thought I was done with painting. It consists of this air pump, 100' of corrugated hose and a hood.
I had originally been using the hood that goes over your head and inflates but its not always perfect and sometimes I get a whiff of paint. I found this mask on eBay, NOS, for $100 and bought it to try. Man, it works so much better than the hood. So much so that I bought a second one to keep around for when this one wears out.
Anyway, if you spray a lot of 2k or isocyanatic paints, I highly recommend having one of these over using a filtered carbon mask.