Snow-covered mountain range with rugged peaks under a clear blue sky, offering a serene and majestic winter landscape.

Our verdict

Extra-warm, durable down belay jacket

Mammut's Taiss Pro Belay IN jacket provides serious warmth when thrown on at the coldest belays. To see how it performs in real conditions, our Covent Garden store manager Alex tested the jacket during a full week of winter climbing on Ben Nevis in Scotland. Andi, our Aviemore store manager also tested the Taiss jacket out in her respective backyard. The New Year kicked off with some favourable ski touring conditions in the Cairngorms, so Andi took full advantage of the fresh snow.

At a glance

Image of 850 fill down insulation

850 fill down insulation

High-quality 850 fill down insulation guarantees warmth, while remaining lightweight and packable. The Nikwax hydrophobic treatment helps the down retain loft when wet and improves drying times.

Image of Helmet compatible hood

Helmet compatible hood

The hood is shaped for an optimal fit over a climbing helmet. You can adjust the hood at the rear to keep it secure when worn without one.

Image of Two-way front zip

Two-way front zip

You can unzip the jacket from the bottom to increase ventilation, provide clear access to your harness belay loop, or improve comfort when you sit down.

Image of Harness compatible hand pockets

Harness compatible hand pockets

Positioned out of the way of a harness or backpack hip belt, these zipped pockets keep your small items secure and accessible.

Image of Internal drop pockets

Internal drop pockets

Internal Powermesh drop pockets are ideal for keeping things close to hand and warm, such as gloves or climbing shoes.

Initial thoughts

Alex: At first, I was sceptical about using a down jacket in Scotland. It also looked bulky and heavy. Once I tried the product around the house, I was pleasantly surprised about how light and unrestrictive it felt. It is as light as my synthetic jacket but warmer.

Andi: I thought the jacket was super light. Maybe a bit too light even for what I wanted to use it for. Once I tried it, it felt really warm instantly with plenty of room for movement. I was very pleased with how it fitted over my shell and gloves with ease.

Fit

Man in a warm, dark jacket and blue helmet standing in snowy mountains, looking upwards, with rugged peaks and a clear sky in the background.

Performance

Alex: The jacket really exceeded expectations. It was lighter and more packable than it looked like in the shop and the DryDown did a great job of keeping the moisture away. It did a great job trapping all the heat and keeping me toasty while waiting for my partner to climb. After a day of climbing, it was nice to have a big warm jacket over a t-shirt without having to wear multiple layers underneath.

Features

A climber wearing winter gear ascends a snow-covered, rocky slope, using ropes for support in a rugged mountain environment.

Final thoughts

Alex: This jacket really impressed me with how warm it is for how light it feels. It worked faultlessly in proper Scottish winter conditions and will become my go-to for future trips. Ideal for winter climbers and mountaineers who need a proper warm belay jacket in cold conditions. It’s also great for anyone spending lots of time standing still in the cold. Warm enough to work well as an everyday winter jacket too.

It has excellent warmth for the weight thanks to the high-quality down and baffle design. Really useful pocket layout that’s easy to use with gloves. The mix of down and synthetic insulation makes it feel practical and well thought through.

Andi: I was after something lightweight, no bulk, that keeps me warm in the often-harsh Scottish conditions. So far, this jacket has ticked all those boxes.

About the testers

Image of Alex

Covent Garden store manager

Alex

I’ve loved outdoor activities since I was a child, but over the past 20 years, it’s become a lot more serious. I go hiking two to three times a year, either hut-to-hut or camping. I also add two climbing trips to the mix: one in winter for ice climbing and another in summer for mountaineering. On my days off, I often go bikepacking or mountain biking. I spent a week in Scotland winter climbing on Ben Nevis. We slept 5 nights in the CiC hut, climbing various routes on the North Face of Ben. Terrain varied from mixed to snow gullies and ice. The weather was also mixed with first few days being very snowy but not too cold and ending the trip with gale force winds and -13C chill. 

Image of Andi

Aviemore store manager

Andi

My love of the outdoors is the reason I moved to the Scottish Highlands.  Even if the weather isn't great, there is something so calming about being out in the elements. During the winter, my main activity is skiing/ski touring. One of the days I tested the jacket, we went up for a bit of ski touring, not too far from Cairngorm Mountain Resort as visibility was very poor. By the time we were transitioning at Marquis Well, wind had picked up, and it was -20 degrees in wind chill. 

Taiss Pro Belay IN

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