I was talking to one of my mentors and he told me it might be a emergency bunker vent, as it has both hand crank and mechanized capabilities. Mine had a coupler for a air line on the intake that had a gasket. It does not have the flat blade blower commonly found on solid fuel blowers, Rather it contains a hybrid squirrel cage fan that actually moves a bit of air. At some point in the future I will see what the water column pressure is. All in all, I am happy with it.