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Sierra Designs Flex Capacitor 25-40 backpack, Birch, front view, contracted

Big, Small, it Does it All.

Meet the pack that does it all. The Flex Capacitor family of packs feature adjustable volume to handle both short and long hauls, and a Y flex suspension system that carries above their weight class. With three sizes in a 25-40, 40-60, and 60-75 L capacity, there is a flex pack to fit your needs. A bucket lid with a stash pocket closes everything up, while dual stretch pockets on the shoulder straps and side of pack cover shove it needs.


  • Expandable Volume
  • 2 stretch mesh side pockets
  • 2 stretch mesh hydration pockets on shoulders
  • Zippered hip belt pockets
  • U-shaped top acces zipper
  • Small stash pocket in lid
  • Ultralight weight
  • Lightweight 'Y' Flex DAC suspension


  • 100D Nylon-Poly Ripstop/420D Nylon Oxford

Tech Specs

  • Capacity: 25-40L / 1525-2440 in3
  • Weight with S/M waist belt: 2 lbs 7 oz  /1.1 kg
  • Weight with M/L waist belt: 2 lbs 8 oz / 1.13 kg
  • Torso Fit: 16" - 19" / 40.6 - 48.3 cm
  • Hip Fit with S/M waist belt: 29" - 32" / 73.7 - 81.3 cm
  • Hip Fit with M/L waist belt: 32" - 35" / 81.3 - 88.9 cm
  • Dimensions (H x W x D): 23" x 11" x 8.5" / 58.4 x 28 x 21.6 cm
  • Suspension: Y Flex DAC
New Badge: Yes

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    Flex Capacitor 25-40

    Out Of Stock