By the turn lock secure seal and no dripping as its predecessor (original mouthpiece). Change problem Lost (old mouthpiece to the hose cut). While drinking the old model was better. In this you have to hold the mouthpiece slightly and sucking front with the teeth (small diameter). Thereafter, the liquid automatically flows back, which requires re-suction of air. Can verhnindern against the opening hole to push through his tongue. When old it was instinctive by biting and sucking. When releasing the liquid did not flow back.