You've felt it before: the vest that bounces every stride, the straps that dig in around mile 10, the constant mental tax of fighting your gear when your focus should be on pace. Most athletes accept it as part of the deal. Here's what most athletes don't realize: your hydration vest isn't supposed to be something you manage. The right one disappears and stays there.

The Nathan AeroZip 1L Unisex Hydration Race Vest is the exact carry system trusted by marathon runners and ultramarathoners who refuse to let hydration cost them time, energy, or aerodynamics.

• Aerodynamic fit that locks to your body. Perforated four-way stretch fabric wraps your torso like a second skin, stable without compressing, locked in without restricting breathing or arm swing.
• Two flasks, zero fumbling. Two oval-shaped 17oz Nathan x HydraPak soft flasks contour your chest for a flatter carry than round bottles. Pull one mid-stride, drink, tuck it back, 34oz always within reach.
• Zip on, zip off in seconds. A full front locking zipper replaces the pullover fight at race morning. Side elastic toggle cords let you micro-adjust fit precisely to your torso.

When a vest moves independently from your body, your core compensates on every stride, wasting energy you'd rather put into pace. The AeroZip's body-contouring fit eliminates that movement. Oval soft flasks collapse as you drink, removing the air pocket that causes sloshing. At 4.8oz without flasks, your body stops registering it as gear within the first mile.

Before your race: Fill both 17oz flasks, one water, one electrolyte mix — and load your mesh pockets with gels in order of use. Everything organized, nothing to think about mid-race.

On course: Pull a flask one-handed, drink, return it without breaking stride. Repeat every 15–20 minutes.

Pro tip: Dial the side toggle cords at home before race day so the vest sits flush against your torso. Two minutes once, locked in every time after.

Ironman athletes and ultramarathon runners who've switched from rear bladders and hip belts report the same thing: the front-carry system is faster, the fit stays put, and the vest disappears by mile three. These are the athletes who stop experimenting with hydration because they've found something that works.

This isn't just another hydration vest. This is 34oz of on-board fluid in 4.8oz of gear, so your only job on race day is to run fast.

What Is the Nathan AeroZip 1L Hydration Race Vest?

The Nathan AeroZip 1L Unisex Hydration Race Vest is Nathan Sports' precision-fit, ultralight hydration vest built for marathon, trail, and ultra racing. Previously known as the Nathan Stealth 1L, the AeroZip is the updated successor with refined specs: a full front locking zipper entry, two oval-shaped 17oz Nathan x HydraPak soft flasks, perforated four-way stretch woven fabric, and side elastic toggle cords for micro-fit adjustability. Total storage capacity is 1 liter / 61 cubic inches. Weight is 4.8oz / 137g without flasks and 7.6oz / 216g fully loaded. 

We've stocked a lot of hydration vests at The Feed, and the question we always come back to is: does it actually stay put? A vest that bounces or shifts mid-race is costing you — not just in comfort, but in the subtle energy tax your core pays to compensate. The AeroZip nails the thing that matters most. The fit locks in. The two-flask front carry is genuinely faster than anything on your hip or behind your back. And the front zip entry is one of those details that sounds small until you've wrestled a pullover vest over your head at mile 0 of an Ironman run. This is the vest I'd reach for.

— Matt Johnson, Founder, The Feed

What You Get:

• Nathan AeroZip 1L Unisex Hydration Race Vest
• Two 17oz / 500ml Nathan x HydraPak oval soft flasks
• Four expandable power mesh front pockets
• One zippered valuables pocket
• Side elastic cords with toggle locks
• Full front locking zipper closure
• Available in S, M, L, XL