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UOG TOP PICK: Light, breathable, and mountain-ready, the Mammut Eiger Nordwand IN Flex Air Vest combines Alpha insulation with an air-permeable shell, making it a top choice for fast-moving alpine missions.
Mammut says:
Active insulation for high-intensity ascents. Tested by athletes as part of our Eiger Nordwand range, this vest can be worn as an outer layer or paired with a jacket. Quick-drying Polartec® Alpha® Direct Polypropylene insulation provides warmth while allowing sweat to escape. The 20D Pertex® Quantum Air outer fabric combines breathability with elasticity for freedom of movement during rock and ice verticals. With a durable design and easy-repair features – including a fixable YKK® front zipper slider and a patch kit for on-the-go repairs – the Eiger Nordwand IN Flex Air Vest is an efficient, versatile choice for alpine adventures.
Our Verdict
At 202g (Medium), it uses Polartec Alpha Direct insulation paired with a 20D Pertex Quantum Air shell. I am a big fan of Alpha for active insulation, and matching it with a lightly wind-resistant, air-permeable fabric feels like the perfect combination. The vest cuts heat efficiently, and the two chest pockets double nicely as dump ports for extra venting. I also appreciate the dropped hem, which enhances coverage and maintains a stable fit under a harness.
The cut is athletic and articulated, giving good freedom of movement, while the partially elastic hem helps it sit securely. The lightweight shell requires some care to prevent abrasion, but the repair-friendly touches, such as a replaceable zip slider and an included patch kit, are welcome additions.
For those who value breathability, packability and quick-drying warmth, this is a technical midlayer that works equally well on its own in calmer conditions or under a shell when the weather closes in.
- Reviewed by Ultralight Outdoor Gear
Features
- Lightweight, durable and wind-resistant 20D Pertex® Quantum Air recycled nylon for high breathability and thermal comfort throughout intense activities
- With PFC-free Durable Water Repellent (DWR) treatment
- Custom-developed Polartec® Alpha® Direct Polypropylene is a lightweight, highly air permeable and fast-drying
- insulation with an optimum warmth-to-weight ratio
- Climbing-specific pattern for an articulated fit and freedom of movement
- 2-way #5 YKK® VISLON® center front zipper with easy-repair zipper slider
- Designed for repair: design and workmanship facilitate repair of the center front zipper
- Two chest pockets with #3 YKK® coil zippers
- Jacket packs into its large chest pocket
- Partially elastic hem for a better fit
- Designed for repair: includes a repair patch kit for quick, temporary, on-the-go fixes
Specifications
- Small weighs: 196g
- Medium weighs: 202g
- Large weighs: 214g
- XLarge weighs: 230g
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Cut: Athletic Fit
Material & Construction
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Main Fabric: Pertex® Quantum® Air
- Lining: Polartec® Alpha®
