A type of endotracheal tube developed circa 1950 and used in lung and thoracic surgery. Has separate bronchial and tracheal lumens, a carinal hook protruding into the right mainstem bronchus and separate bronchial and tracheal cuffs. One major advantage was that it allowed the anesthesiologist to position it using only laryngoscopy and auscultation. Now largely superseded by more recent versions of double lumen endotracheal tubes.