My first reaction to the Fjern Women’s Octa Insulated Jacket was one of surprise. When the label said 'insulated', I was expecting a thicker… well, more insulated jacket. Something with a stuffing – be it down or synthetic.

This is not that kind of jacket. It turns out Octa Insulation is a fabric name and this is a thin jacket lined with Octa Insulation fabric. If you were expecting the equivalent of a belay jacket, you’d be disappointed.

That said, the jacket is a fantastic color and has two decent sized pockets. The wrist cuffs are wide and elastic, with thumb holes, keeping the cold out of your sleeves. There are also toggle draw cord adjustments at the bottom hem of the jacket. The hood has a lightly stiffened peak but has no options for adjustment.

I’ve been wearing this jacket from the tail end of winter, through spring and into summer. That’s included everything from climbing grade one snow gullies in Scotland to walking on Dartmoor to trail running. The first thing I discovered was that I really like the color. Sure, that’s not a very sound reason to approve of a piece of kit – it does have to function and we’ll come to that – but that certainly helped me want to wear it so much.

When I first started wearing it, I fairly quickly noticed there was something odd about the fit. The arm length was fine, as was the length of the jacket, but I couldn’t do the zip up fully without it being physically uncomfortable around my neck. Which is kind of fine in most situations, except when it’s really windy and/or you want the hood up. With no adjustments on the hood, it catches all the air and simply falls down when walking. It’s a little hard to tell whether I ought to have got the size up (the shoulders have a raglan seam so the simple shoulder seam check doesn’t work here), but given the other dimensions fit, and I’ve never had this trouble with any other jacket, it seems very unusual. Or possibly this women’s jacket has been accidentally designed for someone completely flat chested.

All that said, it didn’t stop me from wearing this Fjern jacket a lot. It settled into my layering system as a mid-weight fleece, but taking up much less space in a rucksack. Although it’s described as an insulated jacket, it really is a windproof fleece. The packability also makes it fantastic for trail running in the chillier end of the season. It doesn’t claim to be waterproof, and isn't even slightly water resistant either. In fact, this colorway shows even the slightest wetness – so that’s dark orange splodges in a passing shower, or in my case some attractive back sweat patches when I take my rucksack off. Luckily it’s incredibly quick-drying.

My favorite feature is undoubtedly the elasticated cuffs and thumb holes. I really love a good thumb hole in a jacket – and these are so comfortable. Having the elasticated fabric noticeably improves its warmth factor, especially for situations where a breeze might normally get up your sleeve. I’m thinking of winter mountaineering, when your hands are often above waist height, but let’s be honest most outdoor activities can get windy. The elasticated can make taking the jacket off a bit of a hassle if you wear a watch – it really needs to be worn over the cuff – but on balance it’s worth it. Even more so if you’re wearing it as one above base layer in cold environments.

There is something off about the fit in this jacket. I’m a standard UK size 8 wearing the XS, but it is very uncomfortable to do the zip up above mid-chest height. Basically choking around the throat. The arm length and jacket length is fine though, so simply sizing up might not be an option.

A very easy to wear jacket with few seams and soft lining. The elasticated wrists and thumb holes really add extra warmth and cosiness.

This jacket is not sold as waterproof and is very breathable.

Great durability over a prolonged testing period. Although this colourway does mark easily, it’s also very easy to wash.