Hydration on the go just got easier with our leakproof, insulated Flex Straw Cap. Add it to your favourite Wide Mouth Hydro Flask bottle to easily enjoy cold hydration anywhere. The Flex Straw Cap features a leakproof design and honeycomb insulation, with a flex strap for easy carrying. It is BPA-Free and Toxin-Free. This cap is compatible with Wide Mouth Hydro Flask bottles and is dishwasher safe.