Hydro Flask Standard Mouth 21 oz. Bottle with Flex Cap

Hydro Flask Standard Mouth 21 oz. Bottle with Flex Cap is rated 4.7 out of 5 by 93.
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Hydro Flask Standard Mouth 21 oz. Bottle with Flex Cap
Hydro Flask Standard Mouth 21 oz. Bottle with Flex Cap
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guaranteed for delivery
by Dec 24. details.

Guaranteed Holiday Delivery

Let our no-worries policy put your shopping stress at ease this holiday! Purchase eligible items and choose the appropriate shipping option at checkout. Your order's arrival on or by Monday, December 24 is guaranteed - or it's FREE! See details below.

Legal Terms & Conditions

  • For orders where delivery is not made or attempted by end of day on Monday, December 24, 2018, for the eligible item(s), we will credit your account in an amount equal to the purchase price of the item(s) in accordance with this offer
  • Please note, credits are not automatically applied to your account and must be requested
  • To request your credit, call Customer Service at 1-855-821-6911 starting Wednesday, December 26, 2018 thru 11:59 PM PT Thursday, January 3, 2019
  • Please note that this promotion may be terminated or modified at any time without notice
  • Delivery Methods are listed at checkout
  • All shipping costs are the responsibility of the customer
  • This program applies to:
    • Eligible items indicated with the "Guaranteed Holiday Delivery" tag
    • Guaranteed for Holiday delivery
    • Delivery Methods: Orders received and cleared credit authorization before 11:59 PM PT on Tuesday, December 18, 2018, for Standard Shipping, before 11:59 PM PT on Wednesday, December 19, 2018, for Expedited Shipping, or before 9:00 AM PT on Thursday, December 20, 2018, for Express Shipping
    • Orders shipped to a valid address in the contiguous United States
    • Attempted delivery on or before Monday, December 24, 2018, satisfies this offer
  • This program does NOT apply to:
    • Customized items, special orders, gift cards, items on backorder or cancelled orders (e.g., out-of-stock merchandise)
    • Shipments to Alaska, Hawaii and U.S. territories and possessions
    • Shipments to P.O. boxes or APO/FPO addresses
    • Orders where the required Delivery Method (as set forth above) was not selected at the time of checkout
    • Orders delayed by shipping carriers, acts of war, terrorism, acts of nature, or other events beyond our control
    • Previous purchases
  • For any questions, please contact Customer Service at 1-855-821-6911

Product Information:

Perfect for functional use, the Hydro Flask® 21 oz. Standard Mouth Bottle with Flex Cap makes the perfect hydration companion. The double wall vacuum insulation keeps your hot beverages hot for up to 12 hours, and your cold drinks cold for up to 24 hours. Made from durable food-grade stainless steel with a powder-coated finish, the 21 oz. bottle features sweat-free construction for easy grip in any conditions.

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  • Hydration bottle for the trails and everyday use
  • Capacity: 21 oz.
  • Standard mouth opening for easy, on-the-go drinking
  • Durable, powder-coated design
  • Constructed with 18/8 pro stainless steel
  • BPA free and phalate-free
  • Includes lid for easy transport
  • Hand wash


  • Double wall vacuum insulation
  • Keeps hot beverages hot up to 6 hours and cold drinks cold and refreshing for 24 hours
  • TempShield™ protected sweat-free finish
  • Also compatible with Hydro Flask® Wide Flat Cap, Hydro Flip Lid and Wide Straw Lid

Additional Details

  • Manufacturer’s lifetime warranty
  • Model: S21SX
  • Brand: Hydro Flask
  • Country of Origin: Imported
  • Style: S21SX,S21S


Rated 5 out of 5 by from Nice Bottle Bought this a week ago since I needed something more portable instead of the 32 oz wide mouth. It fits in the cup holder and in the side compartment of my backpack. Water stays cold for a good amount of time, I'm not really expecting something to be ice cold after an entire day nor would I let it just sit all day. If I have a water bottle, I'm drinking it as the day goes and if it's not ice cold anymore, I can always refill it.
Date published: 2017-08-30
Rated 5 out of 5 by from Where I am, my Hydro Flask is there too I purchased this about two months ago and am absolutely in love with it. I am the type of person who loves extremely chilled water after my runs. I throw in a couple of ice cubes and fill it up with water and by the time i get back from my long runs (6-7 miles), it is exactly what I need to quench my thirst. I literally don't go anywhere without my Hydro Flask.
Date published: 2017-07-21
Rated 3 out of 5 by from Great company, not the best tumbler I love hydroflask. I have a 32oz tumbler that I love so I thought I'd purchase a smaller one. I was so excited but I was a little disappointed. I'm a germ freak so this bothered me, the mouth piece that you drink from is always exposed! My hands touched it all day which grossed me out!! I'm a college student so I'm at school all day! By the end of the day I can only imagine how many germs I come in contact with. For that reason, I refurned this product.
Date published: 2017-09-12
Rated 5 out of 5 by from Lives up to its claims I bought this a few weeks ago and am very impressed so far. I took it out to the barn with me on a very hot day and the drink stayed cold even though the outside of the bottle felt warm.
Date published: 2017-05-02
Rated 5 out of 5 by from My daughter loves this bottle! We're now a complete Hydro Flask family! My wife and I got the 40oz wide mouth bottles and we decided to buy this 21oz sports bottle for our 8yr old daughter who is heavily into soccer. She was super excited, she fills it every day whether or not shes got soccer, and takes it everywhere she goes. It's the perfect size, works just as good as the larger bottles and we added the sports top to it as well.
Date published: 2017-08-22
Rated 4 out of 5 by from Great bottle! Keeps liquid cold. Feels and looks great. Dents easily.
Date published: 2018-01-23
Rated 1 out of 5 by from Where you put your mouth is exposed vs wide mouth which is covered I love my 32 oz wide mouth and decided to buy the 21 oz for a smaller option when needed. After drinking from it a few times, I realized that the silver part shown in the picture is where you put your mouth. This might not be a problem for some, but I don't like having the part touching my mouth exposed. In the wide mouth version, the part that touches your mouth is protected under the cover. I will be returning this and buying the 18 oz wide mouth.
Date published: 2017-05-06
Rated 5 out of 5 by from Best Insulated container I've ever had I have the 32oz version - put ice & coke in it before leaving for Disneyland - at the end of the day in 80+ degree heat there was still ice in it & the coke was still ice cold - I've NEVER had a drink container do that - not even a "Tervis" - GREAT JOB in doing your homework & designing a container og this quality.
Date published: 2017-07-24
  • y_2018, m_12, d_13, h_21
  • bvseo_bulk, prod_bvrr, vn_bulk_2.0.9
  • cp_1, bvpage1
  • co_hasreviews, tv_0, tr_93
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