UltraFlask 550 Hybrid Bottle

(17 customer reviews)


UltrAspire introduces yet another milestone in hydration history! The Ultraflask 550 Hybrid Bottle has all the benefits of a softflask but with the conveniences of a hard bottle. The bottle is designed to sit as close to the body as possible to minimize movement when full.  The soft-body shape helps with rapid access, comfort, and squeeze.  The large cap opening easily fits ice cubes and is covered by a high flow push/pull valve. Made in the USA.


UltrAspire introduces yet another milestone in hydration history! All the benefits of the sport bottle without the downsides and all the benefits of a soft flask without the usual problems such as taste and staining from carbohydrate drinks. This great feeling, easy stowing bottle is a hybrid between a hard bottle and a soft flask! The light weight super-squeezable UltraFlask™ stands alone, is fillable and easy to clean, has high flow and fast recharge, is soft, flat and stable against the body, is easily accessed and returned to a vest pocket even when empty, and its great for waist packs too! The UltraFlask 550 Hybrid Bottle is BPA free.

• Simple push/pull nozzle with high flow.
• Soft and comfortable against the body.
• Ultra squeezable with quick recharge.
• Food-grade LDPE and made in the USA.
• Custom printing option available.

Hand-wash. Due to the nature of this ultra-squeezable bottle, it is not recommended for dishwasher use.

Additional information

Weight N/A
Dimensions N/A

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Product Weight (lbs)

Product Dimension (inches) LxWxH

Fluid Capacity

550mL (18.6 fl. oz)

17 reviews for UltraFlask 550 Hybrid Bottle

  1. Mathieu Fortin (verified owner)

    I used two of these flasks with the Alpha 2.0 vest and it was a great combo. The shape is perfect to avoid putting pressure on the ribcage, and they are surprisingly flexible, so they aren’t hard against the body. Good job UltrAspire, your products got me through a tough 100 km race ! Many thanks !

  2. Jim Bosik (verified owner)

    Loving the UltraFlask 550 for the lightness and squeezability. Will be using it for a 50 miler and a hundy this summer. In terms of taking a good swig, can’t be beat. Only suggestion…would be great if it were a tiny bit narrower and taller, since it is not the easiest to get back in to my UD Jurek vest. With that small change it would sell like crazy. All in all, a great product. Thanks!

  3. dj.crites14

    DJ Crites

    UMMMM, Favorite Water Bottle to DATE!!
    For me one of the reasons for using UltrAspire is the construction of this bottle! I was not a fan of how the soft flask versions of other brands collapsed into the pockets and became a fight to get back out. This solved my issue with “trail fishing”.
    The usage of a hybrid bottle soft with a firm shape is amazing. I never have to worry about the bottle loosing shape. The shape of the bottle is very comfortable in general, ie non-traditional bottle shape. Super comfortable to use in all fashions.
    I have 7 of the bottles, albeit some came with other products but personally I like to have 1 or 2 extra bottles on hand for races incase one gets damaged.

    Only personal issue I had when I first purchased, due to habit from other bottle styles I bit the mouth piece and deformed it. And this end does not regain shape after doing so. I have experienced the best way to open and close currently to avoid another damaged end is to open and close by hand. I have since purchased back up caps to help replace any being damaged in the future.

    ::SIDE NOTE:: Buying extra bottle cap ends may be worth while in the long run, just in case UltrAspire discontinues these bottles. I had this happen to me before on another brand and did not want to re-buy the new bottle style. End up finding a discontinued waist belt system on REI and purchased it just for the extra two bottles because the lid cracked.

    All in All this is such a great design and by far my favorite flask/bottle since using vest/bottle systems back to 2012.

  4. Nolan

    This is an outstanding water bottle from UltrAspire! The shape of it makes it super comfortable when in my Momentum vest or my Fitted Race Belt. The material is unlike any other water bottle I’ve used in the past. It’s surprisingly soft, yet structurally sound! And when you combine the pliability of the bottle with the high flow, push/pull valve cap… watch out!! Proceed with caution because you will be hydrated in a hurry! Not that that is a bad thing. Overall, it’s a great bottle for all your endurance needs! Bonus: it fits nicely in the cargo pockets of my pants!

  5. Alexander Humenetskyj

    GET IT! I was a little skeptical of switching from my soft flasks to what looked like a hard flask bottle. However, the UltraFlask 550 hybrid bottle is a perfect combination of both soft and hard making it my new go to bottle. I was pleasantly surprised with this creation. Simple, comfortably soft yet sturdy, high flow like it should be. Well done.

  6. Henry Howard

    I really like the 550 race handheld. While my hands are on the small side, it fits me so perfectly that I forget I am carrying a bottle when I am out on my runs.
    Additionally, it is easy to grab a quick sip or gulp while on the run, and just as easy to secure the cap again — and the top is made of plastic, not rubber like other brands. I have one from another brand that has a hole in the mouthpiece because of the way that it’s made. The hole made it pretty useless in short order.
    The UltrAspire bottle is easy to clean, too. It is easier to separate the sleeve and bottle for washing than it is for other brands.
    With summer and hotter weather on the way, I am glad to have such a useful handheld to take with me on long runs so I can be properly hydrated.

  7. Jenny Velocitas

    It’s light, it’s soft but holds it’s shape, it’s easy to drink from, it fits all the vests, it’s great! I have all the colors!

  8. Doug Williams (verified owner)

    Fragile cap. Second wearing of new vest dropped bottle as I was placing into Momentum 2 holster, cap opening valve broke. All my hydration leaked out.

    • Jodi

      Hi Doug, I will make sure to send you a replacement cap.
      Thanks, Jodi

  9. Bethany Brown

    I really like this bottle. A LOT. I use it with my Basham hydration vest. However, the only thing knocking it down a bit is the cap is very easily deformed. I am on my 4th bottle in 2 months due to this deformability and subsequent leaking (for various reasons). It’s expensive adjustment to have to keep buying new bottles for my vest to get used to how easily this bottle cap can start leaking. I recommend buying additional bottle caps — however, I do not see them for sale separately.

    • Jodi

      I read over your bottle review and wanted to check with you and get your address so I can send you some replacement caps.

      Also, I have included a link below to the small caps which are listed on the accessories page of our website, just in case you need more in the future.

      Thank you for your time! I will talk to you soon,


  10. Jeff Huget (verified owner)

    Excellent flasks. I use two with my Alpha 5.0 vest, one color for sports drink one for water. Really high flow so you can take quick sips, fits nice against your body and are soft so they are comfortable in the vest. We’ll done.

  11. fred (verified owner)

    First, let me compliment Ultraspire for just having these bottles available for purchase on their website; it seems that some vendors (Salomon) don’t even offer replacement bottles for sale.

    First, I purchased the Speedgoat 3.0 Waist Pack (awesome pack, rides well, comfortable) and discovered that the UltraFlask 550 Hybrid Bottle fits my Salomon Sensibelt waist pack even better than Salomon’s triangular bottle (yeah, the one that they don’t have replacements for).

    The Hybrid Bottle’s cap is very impressive–the cap opens and closes easily, I can actually use my teeth to pull it open, and it seals exceptionally well–no leaks ever. The bottle is also free of any plastic smell; I don’t know which plastic is used, but it’s quite nice–soft and does not impart any taste to the water.

  12. Carol Hawkins

    Bought the Basham 4L since it was totally adjustable in fit. Have only worn it a couple of times but I love it. Took a star off because the bottle leaks.

  13. James Lavin (verified owner)

    Love/hate. Great in my Ultraspire vests, great to drink from, squeeze is just right, shape is fantastic, right size, wonderful for a race—-but they leak and leak and leak. The caps are too fragile, the sealing sucks. But they are still my go to bottles—even if half the contents end up in my car. Wish they would make it easy to buy new caps—and make the caps stronger.

  14. EC

    These are great bottles. I use soft flasks also, but these are nice since they hold their shape when you’re drinking from them. 1 of the 1st 2 I had leaked at the cap. The washer was miss-cut, and one section was thinner than the rest. The replacement had no issues. The only problem I have with these is the lettering on the cap. That sounds silly, but the lettering is raised and very rough and really sheds lightweight running shirts. At 1st I thought my vest was rubbing but eventually figured out it was the caps. I shaved off the lettering with a utility knife and it’s been fine since, but unfortunately I have 2 shirts with odd wear patches on the back now. Maybe the lettering is raised for grip? If so, it’s not needed – I’ve had no issues removing the caps after smoothing them out.

  15. rknowles83 (verified owner)

    Great bottles. I used these in a three-day stage race in the front pockets of my Zygos and they worked great. They are easy to open and refill and I never had a problem with them leaking or with the top.

  16. Deanna Springall (verified owner)

    Excellent design! Bottles have an easy-to-use pop-up for drinking. The combination of rigid neck/cap and flexible body makes it very easy to squeeze a sip out whether you’re holding it from below or above. Be careful to thread the cap on correctly or the bottle will seem to leak. Also, it takes a little practice to get it into and out of an UltrAspire vest since those magnets are STRONG. But, I love the bottle and am buying the handheld version for the spouse.

  17. Miles Victors

    My favorite flask to use. While I appreciate soft flasks and their zero slosh nature, the simplicity of these bottles can’t be beat, especially when you need to take them in and out of a pack, belt, or using them as a handheld. They feel great to the touch and the tops work flawlessly, zero leaks. They are also compatible with most of UltrAspires other hydration carrying options, so having extra on hand is always a good thing. I have WAY too many of these, because they just work well and I can have extra bottles for my crew to hand me during aid station stops that are ready to go and slide right in to my vest or belt.

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