The Hydro Flask Standard Flex Straw Cap is perfect to help keep you hydrated—you just have to flip and sip. This leakproof insulated cap can be added to any Hydro Flask Standard Mouth Bottle, so you can enjoy cold drinks anywhere. The straw is easy to trim to fit your favorite size water bottle, while the flex strap makes it easy to carry with you. Plus, it is BPA-free and toxin-free.