Flex Capacitor 40-60L Backpack
Accidental Damage Cover
By adding Accidental Damage Cover, you agree to the Terms & Conditions.
Shipping and return included
- Sierra Designs Flex Capacitor 40-60L backpack
- Hipbelt, fitted
- Cleaned, emptied and inspected before every hire
Carries 40 to 60 litres in one expandable backpack, built for lightweight multi-day trips. Hired with the hipbelt fitted. Every pack is emptied, cleaned and checked over before it goes back out. Most commonly hired by walkers heading out for multi-day hikes, and by anyone wanting to try a lightweight frame pack before committing to buying one.
Your hire equipment is delivered directly to your door in a reusable returnable box or bag.
🚚 Delivery
- Choose your rental start date.
- We recommend selecting a start date 1–2 days before you need the equipment to allow time for delivery.
- We ship using Royal Mail or DPD, depending on the size of your order. We’ll let you know which courier is used.
↩️ Returns
- A pre-paid return shipping label is included in your box or sent via email.
- When your rental ends, simply repack the equipment and drop it off at any Collect+ drop-off point.
- Find your nearest Collect+ location here: Collect+ Store Finder
- Please make sure the Collect+ location accepts the relevant courier (Royal Mail or DPD, as specified on your label).
🔍 Inspection & Security Hold
- Once returned, all equipment is inspected and cleaned.
- If everything is in good condition, your security hold will be released.
- If damage is found, we’ll contact you to arrange payment in line with our Rental Terms & Conditions .
- Expandable Volume: Gusseted front panel opens for 15 to 20 extra litres, then cinches back down for shorter trips.
- Expands Outwards: Volume grows sideways rather than upwards, so a full load stays close to your back instead of towering above it.
- Y-Flex Suspension: A DAC alloy Y-shaped stay runs into the hipbelt to transfer weight onto your hips.
- Zipped Lid Access: U-shaped top zip opens the main compartment in seconds with no roll-top to fasten.
- Ventilated Back: Two scapular pads and a lumbar pad create an air gap between you and the pack body.
- Shoulder Pockets: Two stretch mesh pockets on the straps keep a phone, snacks or a small bottle within reach.
- Hipbelt Pockets: Zipped pockets on both sides for the things you want without stopping.
- Side Pockets: Two stretch mesh pockets take bottles or a rolled waterproof.
- Compression Straps: Two horizontal straps take a mat, poles or a rope on the outside of the pack.
- Simple To Load: One main compartment, a zip lid and a small stash pocket in the lid means nothing to work out before your first trip.
| Capacity | 40–60L (20L adjustable) |
|---|---|
| Packed weight (S/M) | 1.23kg |
| Packed weight (M/L) | 1.4kg |
| Pack size (S/M) | 63cm x 20cm x 32cm (H x W x D) |
| Pack size (M/L) | 70cm x 22cm x 32cm (H x W x D) |
| Torso fit (S/M) | 41–48cm (16–19in) |
| Torso fit (M/L) | 46–53cm (18–21in) |
| Frame | DAC alloy Y-Flex stay |
| Body fabric | 100D nylon-poly ripstop |
| Base fabric | 420D nylon oxford |
| Access | Top load, U-shaped zipped lid |
| Pockets | 2 stretch mesh side, 2 stretch mesh shoulder strap, 2 zipped hipbelt, 1 lid stash |
| Compression | 4 volume gusset straps, 2 horizontal compression straps |
| Sizes available | S/M, M/L |
The Flex Capacitor comes in two fixed back lengths. There is no adjustable back system, so the size you pick has to match your body. Two measurements decide it: your torso length, and the measurement around the top of your hip bones.
How to measure your torso
- Tilt your head forward and find the bony bump at the base of your neck. That is the top of the measurement.
- Put your hands on your hips with your thumbs pointing backwards, so your thumbs meet at your spine. That point, level with the top of your hip bones, is the bottom of the measurement.
- Have someone run a tape measure down your spine between those two points, following the curve of your back. That figure is your torso length.
How to measure for the hipbelt
Measure around your body at the top of your hip bones, not around your trouser waist. The belt sits on the shelf of your hips and carries most of the load, so this is the measurement that matters, not your trouser size.
Sizes
| Size | Torso length | Hip measurement | Weight | Pack size |
|---|---|---|---|---|
| S/M | 41–48cm (16–19in) |
74–81cm (29–32in) |
1.23kg | 63 x 20 x 32cm |
| M/L | 46–53cm (18–21in) |
81–89cm (32–35in) |
1.4kg | 70 x 22 x 32cm |
Between sizes?
The two sizes overlap at 46–48cm (18–19in) of torso length. If you fall in that band, either will carry, and the S/M usually feels more stable with lighter loads. If your torso points one way and your hip measurement the other, size on the torso: a belt at the edge of its range can still be cinched in or let out, but a back length that is wrong puts weight on your shoulders for the whole trip.
If you are unsure, send us your two measurements before you book and we will tell you which one fits. If neither does, we would rather say so than send you out with the wrong size.
A security hold will automatically be added to your Cart. No charge for this will apply at Checkout.
It allows for the possibility of charges in the future for late return, damage fees or non-return fees in accordance with our Rental Terms & Conditions .
How it works
Book your dates
Select your dates, check availability, and hire gear for up to a month.
Add extras
Include any add-ons or essentials to complete your setup.
Delivered to your door
We deliver to your door and include a prepaid return label in the box.
Pack up and return
Repack your gear and return it at a Collect+ drop off when your rental ends.