Rachel Z wrote a review of CamelBak Better Bottle Accessory - 2 Bite Valves/2 Straws on June 6, 2013
It seems like I go through these a lot for my Better Bottle. I'm guessing it's not a bad thing to change it out that often because I don't like it when my water smells/tastes funky. The ends of the straws stretch out after a while and fall off... but that usually takes a long time. The price is right and I love the bottle so I am good with just buying replacement parts.