I bought this to replace an earlier drink bottle that extended from the mouthpiece to the bottom of the whistle. The mouthpiece folded into hiding, but bacteria accumulated in the whistle. In this bottle of Nalgene, dirt can accumulate on the mouthpiece, but it is simpler to keep clean. It is not easy to suck from a bottle. A four-year-old prefers to completely remove the cap to drink from the edge of the bottle. That's how it works.
The plastic part inside the mouthpiece prevents the liquid from flowing out, but causes it to be sucked quite firmly and to get something out of the bottle. For a small child, almost mission impossible. The plastic piece can be removed, but then the liquid drains out more easily.
Good bottle for kids.
Hard to get fluid out. Had to suck really hard.