This large circular HVAC air supply diffuser goes at the end of ducts to spread out the air flow and distribute it to all the places in your building that you need it.
Part of the "JC Lobby" family of models. Get them all here: http://www.peripheralarbor.com/ProjectLondon/

Like this model, but need something a bit different? I take commissions! http://peripheralarbor.com/commission/