Uniflow straws have a valve in the base which keeps the liquid in the straw between sips. They help to reduce air intake when drinking through a straw and are ideal for those who find it difficult to maintain suction on the straw. Uniflow straws can't be used with fizzy drinks or thick liquids. The presence of the valve in the straw base slightly reduces the liquid flow rate compared with standard straws of this diameter. Uniflow straws are extra long at 28cm and can be extended to be 33cm long thanks to a large flexible section. Care Instructions - Uniflow straws are disposible and shouldn't be shared between users. Pack size - Smallold in packs of 15, mulitple colours