I have so many different types of lidded drinkware - from my big Yeti mug, to Starbucks double-walled cold during tumblers, and they all have those great plastic straws, but those straws are impossible to get clean (mold will start growing in them, even if you drink purified water). But, these cleaning brushes are awesome . . . I ran one through what looked to be a clean straw . . . guess what? There was crud on the bristles! The cleaning straws are AWESOME, and the four-pack is a fantastic deal!