We asked Fox to send the medium-sized Utility Hydration for this test – it has the same size reservoir but 12L of storage – but it was out of stock. The size small does feature the same heavy-duty 450D polyester ripstop face fabric and overall layout, it’s just a little lacking in capacity and is something you’d probably chuck on for a short loop, rather than a big day in the hills.

Read more: Best hydration packs for 2021, small, medium and large backpacks

Pull open the top zip and you can access the Hydrapak reservoir, which sits in a nylon sleeve inside the main cavity. There is a mesh pocket in there too, with a handy key fob, but getting to those with a full reservoir inside is awkward. On the front is a fleece-lined pocket with a side zip, but it’s a tight fit and getting your hand in is not easy – this is probably best used for a phone rather than to stash goggles or eyewear.

The back panel and shoulder straps feature a raised foam texture to boost air flow, and this pack is pretty breathable, but we reckon that’s more to do with the size than the effectiveness of the design. Since it’s the smallest pack on test, there is a detachable waist belt. It’s your call whether to use it or not, but without it most of the weight is carried on your shoulders and that means if you pull the straps tight it raises the pack up on your back where it can hit the back of your helmet when descending.

We really like the waterproof construction and handy details like the lockable bite valve and magnetic hose clip, but for a pack this small the price is a little on the high side. It’s also tricky to access tools, and the internal storage feels cramped.