ʻO T fin tube kahi ʻano o ka paipu hoʻololi wela kiʻekiʻe i hana ʻia e ka ʻōwili ʻana a me ka hana ʻana o ka paipu māmā.ʻO kona ʻano hiʻohiʻona ʻo ia ka hana ʻana i ke ʻano o ke apo spiral T tunnel ma waho o ka ʻili paipu.