Sierra Designs Flex Trail 40L-60L Backpack - Wild Dove/Peat

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Explore like a pro no matter your experience level. The Flex Trail ultralight backpack gives you the ability to tailor the pack size to your adventure needs by taking advantage of the horizontal gussets. Cinch it down to a 40L cargo pack capacity for your shorter trips. Expand it out to 60L for your longer backpacking adventures. Continue to customize your backpack with the hardware-based adjustable torso. Keep your essentials close at hand with oversized mesh pockets and zippered hip pockets. The aluminum perimeter frame suspension keeps this backpacking pack lightweight while the support stays strong.


  • Expandable volume for versatility in use
  • Lightweight aluminum perimeter frame
  • Customizable fit with a hardware based adjustable torso
  • Large front stretch mesh Shove-It pocket
  • Zippered hip belt pockets and 2 stretch mesh side pockets
  • U-shaped access to top zipper
  • Zip stash pocket in lid


  • Weight: 1140g
  • Volume: 39 - 56L (2380 - 3417 cubic in)
  • Torso: 15.5” - 21” (39 - 53cm)
  • Waist Belt: 31” - 54” (79 - 137cm)
  • Dimensions (H x W x D): 27.5" x 10.5" x 14" / 70 x 27 x 35 cm
  • No. of Hip Belt Pockets: 2
  • No. of Exterior Pockets: 5

Material & Construction

  • 100D Nylon Honeycomb
  • 420D Oxford


Delivery Details

In-stock items are dispatched the same day if ordered before 2pm (Monday - Friday) or the next working day if ordered after 2pm or on a weekend.

Deliveries are normally next working day for orders over £60. If under £60, we sometimes use a 48 hour service. You will have the option to upgrade to a next day service at the checkout.

Special Order items are dispatched within the timescales displayed after selecting your size.

Most orders are dispatched using DPD Next Working Day.

We use Royal Mail 24 for the more remote parts of Scotland, the Channel Islands and Northern Ireland. Please allow a little extra time for delivery in these areas.

For orders under £60, we normally dispatch using Royal Mail 48 with delivery being made in 2 to 3 days. You will have the option to upgrade to a next day service in the checkout.

A tracking number will be emailed to you for all orders over £60 on the day of dispatch.

For orders under £60 dispatched using an untracked economy service, a reference number will be emailed, but you will not get full tracking, only confirmation once delivery has been attempted.

Other Questions

Sometimes you will see 'Special Order' when selecting your size. For these items, we will dispatch once we have received them from our supplier.

An estimated lead time will be displayed for Special Order items.

Yes, returns are accepted within 30 days of purchase so long as it is unused and still in it's original packaging*.

You can return for an exchange or refund.

Refunds are carried out immediately after receiving your item back. Return postage is at your own cost.

* for safety reasons, we do not accept the return of climbing equipment or underwear once it has been tried on.

All items sold come with a minimum 12 month warranty that covers defects in materials or workmanship.

Certain brands offer an additional warranty. You can find this information on the brands own website, or you can contact us for additional information.

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