What is the Osprey WingStay™?
The goal was simple: reduce soft flask bounce, movement, and slippage inside a running vest. The result: The WingStay™ is a collaborative hydration technology developed by Osprey and HydraPak®. By combining a supportive wing structure with HydraPak's proven SoftFlask design, WingStay helps keep hydration secure without sacrificing accessibility, comfort or packability.
For trail runners, front-mounted soft flasks have become the preferred hydration solution for training and racing. They provide quick access to water, simplify aid station refills and distribute weight more evenly than traditional hydration reservoirs. However, soft flasks can also create common frustrations. As they empty during a run, they become more flexible, allowing them to bounce, shift inside the vest pocket or gradually work their way upward. Even small amounts of movement can affect comfort and efficiency over long distances.
The WingStay™ was designed to solve these problems while preserving key benefits of soft flask hydration.
Why Do Soft Flasks Bounce in Running Vests?
Soft flasks are designed to collapse as you drink, reducing water sloshing and saving space. That flexibility can sometimes create a new challenge. As the flask empties, it becomes less rigid and can move inside the vest pocket. Athlete feedback during Osprey's development of its next-generation running vest consistently highlighted three issues:
- Flask bounce while running
- Flask movement or "flop" inside the vest
- Flasks gradually working their way out of the pocket over time
At the same time, Osprey was transitioning toward a flask-first hydration system instead of including reservoirs with every vest. While runners appreciated the accessibility of front-mounted hydration, they wanted greater stability without making the flasks harder to remove or refill.
The question became simple: How do you keep a soft flask securely in place while maintaining one-handed access and all-day comfort?
Solving Flask Stability Started with the Vest
Before HydraPak became involved, Osprey explored numerous solutions through extensive prototyping. Early concepts focused on the vest itself, experimenting with different pocket designs, retention systems and integrated stiffeners intended to reduce movement. Some improved accessibility, others reduced bounce, but none solved all three problems simultaneously.
As the Osprey product team explains: "A lot of the early iterations only had a stiffener along the back side of the flask. That helped somewhat, but it didn't completely eliminate movement."
The breakthrough came when the team stopped viewing the flask and vest as separate products. Instead, they began designing them as a single integrated solution. Adding a supportive wing structure around the flask stabilized the vessel without changing the vest's fit, comfort, or accessibility.
How HydraPak Helped Bring WingStay™ to Life
Osprey originated the concept and defined the performance challenge while our team helped transform that concept into a durable, food-safe, production-ready hydration solution. Working together, both teams refined the WingStay™ geometry, materials, manufacturing process and long-term durability through multiple rounds of testing.
"HydraPak helped us take the idea across the finish line. We're experts in textiles and pack construction,” the Osprey team explains. “They're experts in hydration systems, materials and manufacturing."
HydraPak's product designers optimized the support structure so it stabilized the flask while maintaining the flexibility, compressibility, and drinkability runners expect from a soft flask. The collaboration also included extensive testing for durability, material performance, and long-term reliability under demanding trail conditions.
Benefits of the WingStay™ System
WingStay™ was created to reduce movement, but the final design offers additional advantages that improve everyday usability.
- Improved Stability: The supportive wing structure helps reduce bounce and keeps the flask positioned securely inside the vest pocket throughout a run.
- Easy Cleaning and Storage: The WingStay insert is removable, allowing runners to separate it from the flask for cleaning, packing, or travel while maintaining the compact storage benefits of a traditional soft flask.
- Faster Drying: Because the insert helps the flask maintain an open shape after washing, air circulates more effectively inside the bottle, allowing moisture to evaporate more quickly between uses.
These benefits became valuable additions to the overall user experience, even though stability remained the primary design goal.
Why Designing the Vest & Flask Together Matters
Most hydration vests are designed around existing hydration products. The WingStay™ followed a different approach. Rather than adapting a vest around an existing flask, Osprey and HydraPak developed both products simultaneously. Designing the vest and hydration vessel together allowed both teams to prototype, test and refine the complete experience instead of optimizing each product independently.
The result is a hydration solution that stays more secure inside the vest while remaining easy to remove, refill and drink from with one hand. Importantly, runners don't have to learn a new hydration system or change how they carry water.
As the Osprey team explains: "It doesn't fundamentally change the fit or design of the vest. It simply improves how the flask performs within it."
The Future of Trail Running Hydration
The WingStay™ demonstrates what's possible when hydration and pack designers solve problems together instead of independently. Osprey's expertise in performance vest design combined with HydraPak's leadership in hydration engineering produced an integrated solution to one of trail running's most common challenges. The result is a hydration solution that helps runners spend less time managing their gear and more time focused on the trail.
