There have been some inquiries about this blower's potential for supplying combustion air for furnaces. I can't directly answer whether or not that's the case (yet), but I happened to need a new DC motor for my home-brew impeller scroll, and guessed this one might be about the right size.
TL;DR; Summary: This unit is dirt-cheap, has a small universal motor (AC or DC), roller-bearings (~30k RPM), solid brush-holders, and has some potential for modifying / hacking. It is not a panacea, there are many potential short-comings. IMHO, the main one is that it relies on internal and air resistance to prevent it from over-speeding and by-pass airflow to keep the windings (24ga / 10amp max) cool.
At it's rated 16k RPM, it's not very quiet, and because of it's ABS plastic (Tg 221*F) construction (even at 2mm thick) is going to be susceptible to internal/external heat deformation. The motor size seems "about right" for a keg-size foundry-furnace.
Overall, I'd rate it medium-level Chinese junk (as opposed to complete Chinese junk). It might be perfect for scrappers, scrapers, hackers, tinkerers who's $20 is worth less than their time. Though you'll have to make the final call for yourself. If you can find a more "solid" blower/motor second-hand, at about this price, don't buy this one.