Icebreaker Affinity Thermo LS Half Zip Review

Taking in the views while ski touring.

Bottom Line:

The Icebreaker Affinity Thermo LS Half Zip is a lightweight, technical merino wool blend base layer for snowy days in the back country. Lightweight with stylish textured patterning, it’s versatile enough to wear ski touring or with a pair of jeans around town.

Icebreaker Affinity Thermo working well on a cold day.

Icebreaker Affinity Thermo LS Zip Neck Observations:

The sign of a good piece of outdoor clothing for me, or any item of clothing for that matter, is if when I am wearing it I don’t even notice it. If I can go through an entire day, through every range of motion that I need to on a day spent ski touring, and not have to acknowledge any pulling or tugging of the garment, then it’s A+ in my books. The Icebreaker Affinity Thermo LS Half Zip definitely exceeded in this regard.

Ski touring in the backcountry of BC.

I’ve had the opportunity to wear the Icebreaker Affinity Thermo LS Half Zip on a few backcountry ski trips this winter dealing with bitter cold and the need for regulating body temperature on the uphill. The Affinity Thermo is rated at 200 (fabrics weight in grams per metre²) which according to Icebreaker is a Lightweight rating, however it definitely has enough weight to be a warm base layer while skinning uphill without a jacket, yet light enough that it doesn’t feel bulky.

Icebreaker Affinity Thermo working great as a base layer.

I thought at first that the quilted pattern was just a nice stylish touch to make garment look more like an actual shirt, instead of looking base layer specific, but turns out that it is the new Icebreaker Thermoquilt fabrication. Essentially the quilted pattern traps warmth close to your body when you are cold and releases it through zoned panels when you are moving. Functional and fashionable; good work Icebreaker!

Ribbed bottom hem and Thermoquilt fabrication.

The ribbed bottom hem is a nice touch as it helps to keep the shirt in place while moving. Another feature that I appreciated with the Icebreaker Affinity Thermo LS Half Zip was the generous sleeve length combined with the thumbholes. There was no pulling or cutting into the web-space between the index finger and thumb, which I have experienced on other makes of shirts before.

Thumbholes with generous sleeve length.

A few more notable features are the gusseted underarms which enable the superb range of motion, the half zip (that doesn’t feel tight around the neck when zipped up) which helps to dump heat quickly when on the move and of course it goes without saying that the purple colour is gorgeous.

Half zip with generous fit around the neck.


Fabric: The merino wool adds natural anti-odour properties and the superfine fibres make the base layer itch free; while the nylon fibres increase the shirts ability to regulate body temperature.

Comfort: Superb articulation and fit meant I didn’t even notice the shirt while wearing it.

Weight: Heavy enough for cold winter days but light enough to not be bulky.

Features: Thumbholes, half zip at neck and the ribbed bottom hem are additional touches that, although not necessary, take the shirt from being good to great.


Price: On the pricey side. In my opinion however, Icebreaker is synonymous with high quality wool garments and quality is always worth investing in.

Buy it if:

You are looking for a high quality merino wool base layer for winter activities. The Icebreaker Affinity Thermo LS Half Zip is also versatile enough to transition from a day in the backcountry to a day spent running errands in town.


More Pictures:

Closeup of Thermoquilt fabrication.

Keeping temperature regulated on the uphill.

Zip neck and thumbhole features.

Author: Spring McClurg

I moved to B.C. with my husband in 2010 after spending 6 years living abroad in Ireland. Originally from a small town in Alberta that was minutes away from the Rockies, I always knew I would return to the mountains one day. I love spending as much time as I can in the mountains, whether it be mountaineering, rock climbing or simply running on the backcountry trails. I love to challenge myself and seek out new experiences.

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