Air Conditioning & Heating Grilles/Ducts never looked so good: Fashionable slim/sleek supply air.
Yes those slim cuts in the will are supplying air to this hallway. They are high velocity slim supply air ducts. Unico is the maker. They can also come in a circular shape as well. These flat ones suit the room far better than a circular one OR the old school rectangular open registers.
These are far more discreet supply air grills that blend well to the wall and are set high to fit in a natural pattern with the ceiling woodwork. Unless you look closely they are hardly noticed.