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Combining design, functionality and comfort for long trail runs and races, the UltrAspire Alpha 4.0 hydration pack features large front drawstring pockets for your UltrAspire bottles (not included).

  • Features

    • Can also hold a 2-liter reservoir (not included) in its bladder compartment
    • Reservoir compartment can accommodate a 2-liter reservoir (not included); removable insulating layer helps keep your gear dry and your water cool
    • Reinforced bottom double-layer, 30-denier fabric ensures durability
    • Easily access essentials on the go with the large passage pocket or zippered side pockets
    • Keep your phone in place in the front pocket with the secure strap
    • ErgoFit™ design enables precise movement, contact and weight distribution to preserve the free motion of your body's biomechanics
    • On-The-Go Pockets™ let you access all core components on the go with minimal effort
    • Distributed Weight™ helps keep the pack balanced to ensure the same comfortable fit, whether empty or fully loaded
    • Load weight is positioned lower on the back and closer to your body's center of gravity at the hips to help preserve energy for the long haul
    • Ultracool System™ helps keep you cool by dispersing heat during intense activity
    • Max02 Sternum™ shockcord securing system creates a comfortable and natural breathing pattern while at the same time keeping the pack secure
    • Shockcord allows for stretch outward and 100% rebound, which keeps the pack snug against your body with no restriction of movement
    • Durable and lightweight fabrics offer a high strength-to-weight ratio; they're placed in high-contact areas and stress points for maximum abrasion resistance and durability
    • Trekking pole attachments
    • Water bottles and reservoir not included


    View all UltrAspire Running Hydration Vests
  • Technical Specs

    Best Use

    Trail Running

    Gear Capacity (L)

    6 liters

    Gear Capacity (cu. in.)

    366 cubic inches

    Reservoir Compatible


    Reservoir Included


    Bottle(s) Included


    Liquid Capacity (L)

    2 liters

    Number of Exterior Pockets



    7 ounces


    30-denier nylon/polyester mesh

    Fits Chest

    M: 34-39 inches

    L: 37-42 inches


    15.5 x 14 x 2 inches



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