These unique straws contain a one-way valve so that liquid stays in the straw even if the straw is moved from the user`s lips, making them suitable for people that are not able to suck strongly. It prevents air being sucked into the drinker`s stomach which can cause pain and discomfort. Suitable for warm or cold liquids, the straws clip easily onto glasses and cups for ease of use and can be washed in normal washing solutions or sterilised with boiling water.