This caught our attention when it was first unveiled at the massive ISPO gear exhibition in Munich last winter, and we’re excited that the wait for its release is finally over.

At first glance the Montane Icarus (Phoenix for women) looks like a down jacket, at second glance it looks like a down jacket, and on closer inspection it looks like a down jacket as well. But – you guessed it – it’s not. It’s actually filled with a brand new synthetic material called PrimaLoft ThermoPlume.

Previous versions of PrimaLoft have rated well in our past Outdoor 100s. It’s a soft and silky synthetic fibre that looks and feels almost exactly like down fill and that isn’t far off the thermal efficiency of it either. And it even has one big advantage over standard down, which is that it’s able to insulate even when it gets wet.

“The big advantage PrimaLoft has over standard down is that it’s able to insulate even when it gets wet."

This new version, PrimaLoft ThermoPlume has all of these same traits, however the fibres have a slightly different structure. Sounds like a small and insignificant change, but it’s actually far from it. The consequential impact of changing the structure of the fibres is big.

In an industry first, these ThermoPlume fibres can be blown into the baffles of a jacket with the same equipment used for down jacket manufacturing. It’s a significant development in the outdoor industry as it means that manufacturers can now quickly and easily switch between synthetic fill and down without big changes in process or equipment.

It also means that synthetic jackets can now aesthetically mimic down jackets to an even greater degree by utilising the exact same stitch through micro baffle construction – as you can see here with the Icarus, which is one of the very first products with PrimaLoft ThermoPlume technology.

A down jacket that still works in the wet. Photo: Chris Johnson.

A down jacket that still works in the wet. Photo: Chris Johnson.

PrimaLoft have rated well in our past Outdoor 100s. It’s a soft and silky synthetic fibre that looks and feels almost exactly like down fill. Photo: Chris Johnson.

PrimaLoft have rated well in our past Outdoor 100s. It’s a soft and silky synthetic fibre that looks and feels almost exactly like down fill. Photo: Chris Johnson.

It also isn't far off the thermal effiency which is provided by down, either. Photo: Chris Johnson.

It also isn't far off the thermal effiency which is provided by down, either. Photo: Chris Johnson.

It uses the exact same stitch through micro baffle construction as a down jacket. Photo: Chris Johnson.

It uses the exact same stitch through micro baffle construction as a down jacket. Photo: Chris Johnson.

The fill in the Icarus has a thermal efficiency similar to a 550 fill power down jacket, so it’s not something to bank on as your only insulator on a long winter hike in the mountains, but it’s an ideal layering option, or something that should do the job on low-level autumn walks or milder winter days. It’s also suited to anything fast and light, say, if you’re running or climbing in the mountains and need to pull on a layer while you’re stopping to catch your breath and enjoy the view.

Useful features that should help to protect the wearer from the elements include a water resistant and windproof Pertex Quantum Eco outer fabric, an internal storm flap underneath the main zip, deep handwarmer pockets and a snug hood which is designed to fit comfortably under a climbing helmet.

There are other features that make this suitable for climbers. For instance, the arms are long and articulated so that the jacket’s hem won’t ride up when you’re reaching upwards and the handwarmer pockets are positioned so that they can still be accessed when you’re wearing a harness.

One final thing to note is the cost. We’d say £140 is a fair price for a good-looking jacket that uses a brand new form of insulation.

Montane Icarus Jacket