Sierra Designs Flex Capacitor 25-40L Rucksack

25-40 Litres / Internal Frame
Weighs 1106g (Sml/Med size)
Code: SS20685
  • £139.99
  • (FREE Delivery on orders over £15)
  • RRP £149.99
+ In Stock Now | Usually dispatched within 24 hours

The Flex Capacitor is a modern classic, renowned for its light weight, class-leading versatility, and innovative features. This is the 25-40L version, an excellent size for everything from days out in the hills to self-supported weekends away.

Sierra Designs says:

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.

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More than a daypack while also more streamlined than a full backpack, Sierra Designs’ Flex Capacitor 25-40L Rucksack is the ideal size for most adventures, perfectly capable of carrying enough kit for a week away without the excess bulk that accompanies larger packs. Built around a Y-Flex suspension system, the Flex Capacitor is surprisingly burly for its low weight, with a well-padded lumbar and a wide hip belt to better handle heavier loads. The pack itself is constructed from a primarily from 100D Nylon-Poly Ripstop, guaranteeing durability and water-resistance while keeping the weight to a minimum. 400D Nylon has been used in the base of the pack, to better protect against rocky campgrounds and long-term use.

The expandable volume of the Flex Capacitor is its greatest strength. Where most expandable packs do so with a longer body, the Flex expands its circumference instead, making it a far more comfortable pack when fully opened. This also provides a far greater range than most of its competitors – while many similar packs only manage 10L of expansion, the 15L offered by the Flex Capacitor make it a pack that can happily accommodate everything from quick missions to ultralight multi-day excursions.

The U-shaped access to the pack body is a beautifully simple solution to the heavy lids featured on many similar packs, and makes for a rucksack that is refreshingly easy to pack and surprisingly spacious. The Flex Capacitor veritably swallows gear, while still providing dedicated space for a hydration bladder and keeping a small zipped essentials pocket in the roof, ideal for navigation kit and snacks. The finishing touches are all present too – there are two ice axe loops, a pair of roomy hip belt pockets, and four stretchy mesh pockets; two on the sides of the pack body complemented by one on each shoulder strap. The mesh pockets are useful additions, yet have gone mostly unused as they’re too small for essentials such as bottles and maps. All-in-all, the Flex Capacitor 25-40L is a great mid-size pack that excels when weight and a low pack size are a priority.

- Reviewed by Ultralight Outdoor Gear

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Help and advice: Choosing a rucksack at Ultralight Outdoor Gear
  • Expandable Volume
  • 2 stretch mesh side pockets
  • 2 stretch mesh hydration pockets on shoulders
  • Zippered hip belt pockets
  • U-shaped top access zipper
  • Small stash pocket in lid
  • Ultralight weight
  • Lightweight 'Y' Flex DAC suspension
  • Capacity: 25-40L
  • Weight with S/M waist belt: 1106g
  • Weight with M/L waist belt: 1144g
  • 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
  • Materials: 100D Nylon-Poly Ripstop/420D Nylon Oxford
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