The Flip Spout tops are replacements for the adult "Summit" style bottles and will also fit the "Boulder" style and "Perk" bottles to give you added value and versatility. A straw and ruler are included so you can easily trim to the length you need. We suggest you err on the side of cutting a little longer, as you can always trim more if needed. If you have an older bottle with 2013 stamped on the bottom or not dated, this top may not fit. If you are not sure if this top will fit your bottle, please contact customer care.