The Flex Capacitor backpack

The Flex Capacitor backpack from U.S. brand Sierra Designs is an award-winning, lightweight modern pack.

The backpack is available in three colours and three volume sizes.   

The Flex Capacitor family comprises 20 – 40L, 40 – 60L, and 60L – 75L models, all of which feature adjustable volume to handle both short and long backpacking trips – where most expandable packs increase volume with length the Flex Capacitor expands its circumference instead for what the company says is a far more comfortable pack when fully expanded.

The Y-Flex suspension system provides comfort under load, and there are multiple stash options: a bucket-style lid with a stash pocket secures everything, while dual stretch pockets on the shoulder straps and side of the pack allow you to stash and easily access items.

The Flex Capacitor is robust for its low weight, with a padded lumbar support and wide hip belt to spread loads evenly. Construction is mainly 100D fabric, guaranteeing durability and water resistance, while keeping weight to a minimum. The pack base features 400D nylon, to add more durability and protection against rips, tears or abrasions.

The Flex Capacitor is hydration system compatible, plus its hydration sleeve doubles as a removable summit sack.

A small zipped essentials pocket in the lid is suitable for a compass, phone or snack, and the pack also features two ice axe loops and hip belt pockets.

The Flex Capacitor is available in Bearing Blue, Birch or Peat colours, and prices are £160 for the 20-40L, £175 for the 40-60L, and £190 for the 60-75L pack.

Specs

S/M Torso

• Capacity: 39-56L
• Weight with S/M waist belt: 2 lbs 9 oz  (1.16 kg)
• Weight with M/L waist belt: 2 lbs 10 oz (1.19 kg)
• Torso Fit: 16″-19″ (40.6-48.3 cm)
• Hip Fit with S/M waist belt: 26″-38″ (66-97 cm)
• Hip Fit with M/L waist belt: 33″-48″ (84-122 cm)
• Dimensions (H x W x D): 27.5″ x 11″ x 10″ (70 x 28 x 25.4 cm)

M/L Torso

• Capacity: 42-60L
• Weight with S/M waist belt: 2 lbs 9 oz  (1.16 kg)
• Weight with M/L waist belt: 2 lbs 10 oz (1.19 kg)
• Torso Fit: 18″-21″ (45.7-53.3 cm)
• Hip Fit with S/M waist belt: 26″-38″ (66-97 cm)
• Hip Fit with M/L waist belt: 33″-48″ (84-122 cm)
• Dimensions (H x W x D): 27.5″ x 11″ x 10″ (70 x 28 x 25.4 cm)