Flip it and sip it with the Hydro Flask 21 oz Standard Mouth Bottle With Flex Straw Cap. With a comfortable, flexible handle, the closeable, leakproof straw cap is easy to open and close with one hand, for on-demand hydration. Double-wall insulation keeps drinks cold up to 24 hours for cool refreshment. The slim design fits most cupholders and is dishwasher safe.