Ultraspire Alpha 4.0 Unisex Hydration Vest


  • synthetic
  • ERGOFIT - The human body is complex with intricate detail and function. The same attention to detail is present in the design of our packs to enable precise movement, contact, and weight distribution which ensures that there is never any inhibition to the biomechanics of the human body
  • SHOULDER STRAPS - Human shoulders aren’t straight, so a pack’s shoulder straps shouldn’t be either. Longer straps allow the back portion to sit deeper on the neck to prevent any rubbing. This addition in length helps to create slope as the straps come over the top of the shoulders and around the neck following the natural curve of the body. The harness then follows an S curve around the arms and chest area to avoid any hindrance to the running motion
  • ULTRACOOL SYSTEM - When the human body exerts force, 80% of the power it generates is converted to thermal energy. This means that most of the energy you use when running, climbing, or doing anything else is lost and becomes heat. The hotter you are, the worse you perform. This system allows you to maintain a lower body temperature by dispersing heat during intense activity, keeping you performing at the highest level
  • SMALL FOOTPRINT & ULTRACOOL MESH - Anatomically engineered, the pack covers only what is necessary on the body to keep it secure thus allowing for your temperature to remain cooler during heavy energy exertion. The most breathable mesh on the market, this 3-layered, large holed honeycomb mesh is made from polyester which helps to draw moisture away from the skin without absorption
  • MAX02 STERNUM - The Max02 Sternum is a shock cord securing system that helps create a comfortable & natural breathing pattern while at the same time keeping the pack secure. The shock cord allows for stretch outward and 100% rebound which keeps the pack snug against your body empty or fully loaded with no restriction of movement


Brand: Ultraspire

Product Code:



In Stock
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This is the pinnacle of design, functionality, and comfort. Now entering its fourth iteration, this pack has had unprecedented amounts of care and attention placed into every square inch. The larger front pockets which feature a drawstring are perfect for holding any of our bottles. In addition, the Alpha 4.0 can also hold a 2L reservoir in its bladder compartment. The Alpha 4.0 features an insulated layer piece that can help keep your gear dry while it’s in the pack, cool you off, keep your fluids cool or warm, or you can remove the insulated layer all together.



  • Rapid access pockets
  • Magnetic clasps
  • Large zipper pulls
  • Dual sided removable insulated reservoir compartment
  • Extra soft no chafe binding
  • Secure drawstring pocket
  • Large & flat front pockets
  • Easy access passage pocket
  • Double layered 30D fabric reinforcement at the stress points
  • Trekking pole attachments

Weight: 10 oz (283g)

Sizing Range: Sm, Md, Lg

Volume: 366 c.i. (6L)

ALPHA HYDRATION VEST RUNNING TECHNOLOGY alpha 4.0 race vest alpha 3.0 race vest hydration astral 3.0 race vest Alpha 4.0 Alpha 3.0 Astral 3.0 Hydration Included Not included 2 x 550 mL UltraFlask 2L bladder Sizes LG (37"-42"), MD (34"-39"), SM (31"-36") Small, Medium or Large Women Specific - Universal (26″-50″) Weight 10 oz (283g) 12.2 oz (345 g) 13.6 oz (386 g) Capacity Up to 3 L Up to 3 L 425 c.i. (7 L) brand history information
Product details
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  • ASIN: B07TWYL19L

Fits well, no to very little bounce even on hard down hill runs on technical terrain.

I’ve put over 100 miles on my Alpha 4.0 using both a 2L bladder and two Ultraspire 500ml soft flasks. I usually carry my iPhone 7 Plus, as well as a key fob and a gel or two. I’ve used the rear shock cords to secure a long-sleeved shirt that I removed when I got hot.

The pack doesn’t bounce or chafe, and there seem to be enough storage pockets and shock cords for everything I could need. Plan on using this for 50- and 100-mile ultras through mountainous terrain. I have every confidence it will do the job well.

Great pack!