Zygos 5.0 Hydration Pack

(12 customer reviews)


Since the first iteration of the Zygos, tens of thousands of runners have utilized this high-capacity 14 liter race vest. The lightweight and comfortable wrap around design complimented by the ErgoFit Harness ensures the Zygos 5.0 will be stable, comfortable, and hindrance free. The pack’s MaxO2 Form adjustable closure system secures and adapts to the pack’s load. This innovative system can conform the pack to the body using a single pull. Similar to the MaxO2 Sternum, this system allows the pack to remain secured without impeding natural breathing. Featuring 8 on-the-go pockets there are 2 zippered shoulder pockets, a dual 4-way stretch mesh pocket, a pair of stretch mesh pockets (one of which is zippered and suitable for carrying a large cell phone), a zippered side pocket, and a magnetically closed side pocket. The main back compartment has been reinforced at the stress points with XT fabric which contains stronger than steel ripstop fibers. This pack includes a 2-liter reservoir that fits into the removable insulated bladder compartment. Available in 3 sizes to ensure a perfect fit.


  • Recommended Use:
    Versatile Pack utilized in any run scenario, training or racing.


    • Lightweight, soft, breathable, but strong, large-holed mesh pulls moisture away from the body to keep skin dry and cool.
    • Silicone and PU coated feather-weight nylon fabrics resist water, abrasion and tears.
    • Max O2 Form™ for unrestricted breathing while maintaining a stable pack. Uses shock cord with good stretch for unrestricted breathing but also good rebound on the stretch for a stable ride. Patent Pending.
    • Plush feeling micro-fiber polyester edges, soft and non-abrasive against skin and clothing.
    • Sweat proof webbing—won’t absorb water or get saturated and heavy.
    • Safety stitched bar tack on all stress points.
    • Quiet, bounce free, easy to see and use, zipper pulls.
    • Zig zagged stitching over elastic for ultra-durability, increased stretch and rebound.
    • Simple, fast, easy in and out bladder attachment.
    • Magnon pocket for sweat-free pills, with automatic magnetic closure for rapid access to pills and other essentials. Patent pending.

Fit:  Unisex
Size(s): Small (30″-36″), Medium (32″-38″) or Large (34″-42″)
Color:  Pitch Black
Hydration (included):  2L Reservoir
Bottle Compatible (not included):  UltraFlask, Formula 250, Human 20 oz 2.0, or Collapsible Bottle
Capacity: 854 c.i. (14L)

Additional information

Weight N/A
Dimensions N/A

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Fluid Capacity

2 L (70 fl. oz) Reservoir

Total Volume

14 Liters

Weight (Includes Reservoir)

16.0 oz (454g)


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12 reviews for Zygos 5.0 Hydration Pack

  1. Franck TJ (verified owner)

    The Zygos is very well designed, convenient, and looks durable. The volume to store food and stuff is great and enough for a 50-mile autonomous race. The 2 liters hydration pack is well kept in place and you can insulate it with a smart insulation layer (that can be removed). I noticed small details that make the difference. I like very much the Zygos. I ran 3 hours with it and was happy with the overall experience. I’m ready to go for the 5 hours run in my training plan confidently.

  2. Nathan Dorward (verified owner)

    I love the fit of this pack and the arrangement and stretch of the pockets. It’s the most comfortable vest I’ve ever worn right out of the packaging. Runs longer than 6 hours are no problem with this vest.

  3. Lori Pratt Smith

    The Zygos 5 vest is the best! The new front adjustment system works great and is so versatile. I have a very small torso, so fit of an my running vests has always been a problem. With this pack I moved the attached hooks to the levels that fit best for me and there is no bouncing weather pack is full or almost empty. Easy to tighten it while on the run too. I have used it for a pace duty at a high mountain 100 mile run and for a shorter race so far and has met all my needs.

  4. Daniel Hopping (verified owner)

    AMAZING product! This race vest truly has it all! Just finished a 30 mile training session and it far exceeded my expectations. Ton of storage areas, easy access to gear, insanely comfortable. The form fitting system is amazing as it adjusts to your body and moves with you. You will forget you are even wearing it at times. Just put it on right out of the package and get out there and log some miles! If you are looking at 30 miles or beyond, this is the pack you must own. I can’t wait to take this out on my 50 mile ultra in October and then my 100 miler in April. Thank you for an amazing product, keep doing what you are doing Ultraspire! Also, I highly recommend purchasing two Ultraflask 550 Hybrid bottles! They fit in the pack perfectly and the form of them molds right against your body in the pockets.

  5. Greg Ryan (verified owner)

    Perfect vest for long ultras that require lots of gear. Performed great for 35 hrs. in a mountain ultra.This vest can fit it all with perfectly placed storage options. The fit is very comfortable.Excellent, breathable material. I can’t imagine a better vest.

  6. John McAlister

    I used this vest for the CCC at UTMB this year and it was fantastic. I was easily able to store all of the UTMB required gear while keeping key items such as food and hydration in smaller storage pockets that I could easily access. The vest felt comfortable throughout the 100K mountain race.

  7. Daniel

    Don’t know where to give reviews to company. Want to make it known that the customer service is the best I have ever received. Zach I believe was his name, his help with phone order adding to online purchase, was fast and precise. I have used the light system at Moab 240, and this vest on shorter runs. Look forward to running with more ultraspire gear at the Rocky Raccoon 100. Team Ulraspire you rock. Thanks

  8. Sterling Pierce

    I bought this exceptional pack to run R2R2R of the Grand Canyon. It performs beyond what I thought it would. The ease of access was great. Everyone else kept asking me to get stuff out of their packs for them. I didn’t have to ask because I could do it myself. The only time I had to take it off was to refill the water bladder and to get those items you hope you don’t have to use. Ultraspire killed it. Zygos 5.0 is exceptional. I am actually getting rid of all my other water carriers and using this one no matter what activity I am doing.

  9. Catharine My

    I really loved this bag the couple of times I’ve used it – but when I used it to take my dog and myself on a long day hike/trail run in mixed conditions (bottom of the trail was hot and rocky, top was snowy and windy) – it fit everything that I needed, including doggo’s gear (food, bowls, water, poop bags and poop). But it kept everything I needed secured and I didn’t need a massive pack to carry my gaiters, crampons, poles, layers, food, water, and etc. And the compartments were great to keep my snacks and doggo snacks handy – and a side pocket to keep the doggo poop separate (sorry – this is super important for me). The only improvement would be to have a little more cord to go over my lady melons.

  10. kristinaroepke2015 (verified owner)

    I am a 170lbs 5’9″ female and the medium fits kind of tight on me. It is good because it reduces the bouncing when it is filled with a 2L bladder and two 500ml soft flasks. I like the extra room in the back and I have not gotten a friction burn yet while running on an 85F day for 20mi. I had an osprey duro 1.5L and it feels flat by not conforming to the body. The duro sloshes a bit more too. I recommed the zygos 5 because it conforms to the body and it has thicker elastic chest ties than the salomon advanced skin 12. I picked this because the salomon felt flimsy et the elastic ties for the chest could break easily. I am not rough on my gear but I do not want it to malfunction in the middle of an ultra. The last part is I really like the shoulder zip pockets by the collar bones because they are perfect for keys or gels.

  11. Ethan Banks (verified owner)

    5’11” 195lbs male trail runner. Bought a large, and it fits me like it was made for me. Bought as an upgrade to my Salomon Adv Skin 12, because I was frustrated by how I had to load it. The pockets on the Zygos are the biggest reason I bought it, and no regrets.

    The Zygos 5 has two zip shoulder pockets that seem like a small thing, but change the game for me. Satellite tracker in one, headlamp in the other. Beautiful. Ride great, no bouncing or chafing.

    I use the zip pocket on the left sternum for my phone. Easy to get in and out whether a soft flask is loaded or not. Magnet side rib pocket is easy to load and work one-handed.

    And then there’s the rear pouch. Holds my essentials bag, at least two layers depending on how heavy they are, hat and gloves, and some food. Plus there’s an internal zip pocket with a clip that hold keys and wallet. And while the Salomon pack would transmit sweat into whatever I’m carrying in the back and my layers would get damp, I pulled a dry grid fleece out of the back after an 8 hour run in the Zygos.

    Loading and unloading the water bladder is also easy with this pack. Even with the pack full, I can get the bladder back in with just a few shakes. Less fighting than I’ve had with other packs.

    For the way I like to load out for a long run, this pack is perfect.

    Only one complaint. The water bladder clip with its fabric loop and pull tab is too much material to get in and out of the top of the bladder without fighting it. Too snug. If you’re trying to get through an aid station in a hurry, forget about it. I’m going to mod this somehow, because if you don’t use the clip, the bladder bounces around a little as it drains.

  12. Jamie Farley

    I am 6′ 1″ and 185 pounds. The medium was way to small and tight. The large was way to big but I went with it since the medium was not an option. I love all the storage options in the vest but am very disappointed there is not an option to tighten the pack under the arm pits. I did Fat Dog 120 which had a bunch of required gear and the pack was heavy. All the weight ended up riding on my shoulders and my back was killing me. The draw string tightening system kept loosening up when I was running. In addition, since the synch system kept loosening, the pack would move a bit causing some minor chaffing on my back. In general, I am a huge fan of Ultraspire products. I love the tightening strap system on the Legacy 2.0 pack and wish there was a pack like it with the storage capacity of the Zygos 5.0.

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