The invention relates to a multifunctional applicator 6 for mobile use having an applicator plug 7, a supply tube 8, a Y-piece 9, fork tubes 10 and a nose piece 11 with prongs 12, wherein the applicator plug 7 comprises a pressure chamber 21 that has a humidifier interface 17 for connection with a high flow therapy device 1, an oxygen supply port 13 having an opening diameter of at least 1 mm, and a therapy air supply port 14 for the supply tube 8, the humidifier interface 17 and the oxygen supply port 13 within the pressure chamber 21 are both in fluid communication with an upper and a lower valve seat 23, 25 that are provided with a seal 22 and a valve body 24 being movable between said valve seats 23, 25 and said valve body 24 being subjected to a force by a helical compression spring 26 from the direction of the oxygen supply port 13 and on the other hand being pushed against the upper valve seat 25 by an actuating element 28 of the high flow therapy device 1 when the applicator plug 7 is locked in place on the high flow therapy device 1.