Flip and Sip. Hydration on the go just got easier with the leakproof, insulated Flex Straw Cap. Add it to your favorite Wide Mouth Hydro Flask bottle to easily enjoy cold hydration anywhere. The Cap is not intended for use with carbonated beverages or hot liquids. Fits all Hydro Flask Wide Mouth Bottles Easy to trim to fit your favorite Hydro Flask Flex Strap is easy to transport and comfortable to carry Honeycomb Insulated cap for maximum temperature retention Dishwasher safe Leakproof when closed so you can reliably sip and transport your refreshment without worry BPA-Free & Toxin-Free Removable components for easy cleaning