ɪt kənsˈɪsts əvən ˈɛɹfɔɪl, vˈɜːɾɪkəl ænd ɡɹˈoʊsli ˈoʊvɔɪdəl tˈuːb, wɪð ɐ mˈoʊbəl flˈæp wˌɪtʃ ɪmpɹˈuːvz ðə sˌɛpɚɹˈeɪʃən bᵻtwˌiːn ðɪ ˈɪntɹədˌoʊz ænd ˈɛkstɹədˌoʊz.
It consists of an airfoil, vertical and grossly ovoidal tube, with a mobile flap which improves the separation between the intrados and extrados.