Hydration on the go just got easier with the leakproof, insulated Flex Straw Cap. Add it to your favorite Standard Mouth Hydro Flask bottle to easily enjoy cold hydration anywhere. Features: a Leakproof when closed a Straw is easy to trim to fit your favorite Hydro Flask a Flex Strap is easy to transport and comfortable to carry a Insulated for maximum temperature retention a Removable components for easy cleaning a BPA-Free a Dishwasher safe a Not intended for use with hot liquids