Will Renwick tests out a Kjus technical midlayer that uses the impressive Polartec Alpha

After Daniel Neilson’s recent review of one Mammut’s jackets with Polartec Alpha I had been looking forward to trying out the insulation myself.  It’s supposed to be warm and breathable, as well as being packable and fast drying. All down to its blend of synthetic fibres with woven layers.

I was offered to try it out in the Kjus FRX 3D. It’s technically a midlayer for skiing but I reckoned it would make a useful option for a May hike of the West Highland Way I had planned; I’d wanted something that I could wear just about non-stop. And it turned out to be just that.

Once I had it on it stayed on for most of the 100 miles of the trail, keeping me warm at night and comfortable when going at a good tempo. In terms of its ability to repel water the woven outer fabric called HeiQ Barrier performed really well, meaning I was able to keep it exposed while waiting for any short showers to pass. When the rain got heavy it was also fine underneath a shell.

It only felt a little clammy once the hills got bigger. Still, for walking in May this is understandable.

In terms of the jacket being packable and the insulation hard-wearing, I really gave it a good testing – mostly on the train. I was sat on it during the long journey there then had it squeezed into my bag on the even longer journey back, and was confident – thanks to the stretchy formation of the Polartec Alpha – that it could put up with this.

One of the things I feel that the jacket is let down by a bit is the lack of an adjustable waist hem. It only has partly elasticated sides and these didn’t hold tight enough around my waist so some heat was able to escape. This isn’t the case with the cuffs though, their sleek textured elastic worked well.

The biggest downside to the jacket is its lack of pockets. It only has zipped handwarmers and that’s it. So don’t expect anywhere to keep a map or anywhere to store things while wearing a hipbelt. There are a variety of other jackets in the Kjus range that offer jackets with more storage – maybe they wanted to keep things simple with this one.

Perhaps this lack of pockets is a small quibble, particularly when the jacket’s Polartec Alpha performed so well for me. I think it would make for a great autumn option and a good winter one when worn under a waterproof outer.

You can find it in multiple colours and in either a hooded or hoodless version.