Hydro Flask Standard Mouth 21oz Flex Cap

This cap fits a standard 21 ounce flask and is the perfect go-anywhere companion. Read more >
Hydration on the Go. Our 21 oz. flask is the perfect go-anywhere companion on your busiest days. It stashes easily in a small shoulder bag, your pack’s side pocket, or your car cup holder, and holds enough to keep you going for hours without weighing you down. Now with our new Flex Cap for ultimate portablity.
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