The new model for the Klean Kanteen loop cap is deemed far better than the others. This is because the spout is now made from polypropylene, and it's leak proof.
Its attachment loop means that it can be quickly fastened to a variety of objects, including bikes and rucksacks. The cap fits in all of the Kanteen Classic sizes as well.
The cap contains no toxins, and it is also safe to put in a dishwasher.