Designed for women who enjoy winter activities in the mountains, this Icebreaker W M 260 Vertex LS HZ AlpGeo zip-up top is ideal for those seeking a versatile thermal base layer—just as comfortable under a ski jacket as it is worn on its own during a snowshoe hike. Its 100% merino wool construction at 260 g/m² provides a balance of warmth and breathability, without the use of any synthetic fibers derived from petrochemicals. The half-zip at the front allows you to quickly adjust ventilation based on activity level and conditions.

The 260 g/m² merino wool in the Icebreaker W M 260 Vertex LS HZ AlpGeo: natural warmth and comfort

The merino fiber used has a micron count of 18.9 µ, placing it in the category of particularly fine fibers that are soft against the skin, with no itchy sensation even during long sessions. In addition to this fineness, it offers natural odor resistance—an intrinsic property of merino wool that prevents discomfort during extended days on the slopes or on winter hikes. The 260 g/m² density ensures effective thermal insulation in cold weather, while maintaining sufficient breathability to accommodate varying levels of exertion. The fiber is annually renewable, recyclable, and biodegradable, and does not release plastic microfibers during washing.

A design engineered for freedom of movement and layering

The fitted cut of this garment makes it easy to wear under a midlayer or jacket, without creating unnecessary bulk that would hinder movement. Flatlock seams minimize friction and irritation over time, while offset shoulder seams reduce pressure points where a backpack or harness straps might rest. Underarm gussets round out the design by allowing for a wider range of motion, particularly when pushing off with poles or performing skating movements. The slightly longer back hem provides better coverage on the back when leaning forward, preventing areas from being exposed to the cold.

Active temperature regulation thanks to the half-zip

The half-zip on the front is a practical feature for managing your temperature throughout the day. On the ascent, simply open it partially to release excess heat without having to take off any layers. When you’re stopped or on the descent, you can quickly close it to retain the accumulated heat. This simple versatility is particularly valuable during activities like ski touring or snowshoeing, where periods of intense exertion alternate with moments of inactivity.