At a glance Plusses: Very warm, athletic fit, snug hood, well constructed Minuses: Untreated down, expensiveFeatures: Designed for harsh winter conditions and stuffed with generous amounts of 800 fill-power down, but weighing just 380g (310g - w), the L3 is the warmest jacket reviewed. The DWR-treated nylon shell helps keep the down dry and the wind out. The hood can be worn under or over a helmet, and the single drawcord at the back provides a tight fit when cinched tight. The only drawback is that it pulls the hood back near the ears, which exposes more cheek than I’d like in cold conditions. The jacket also has a baffled centre zipper with good chin protection, two zippered hand pockets which double as stuff-sacks and an adjustable hem. The asymmetric elasticated cuffs are a nice touch and provide a tight fit around the wrists. Fit: The L3 has a fitted athletic cut. The slim body and tapered sleeves minimise dead space and maximise loft without restricting movement. The articulation of the jacket is excellent. The tight fit around the forearms ensures the sleeves don’t fall when your arms are raised. The longer-than-usual torso prevents the midriff from being suddenly exposed to the elements. Comfort: The narrow horizontal baffling provides a hugging fit that doesn’t limit movement. This helps make the jacket feel warm from the moment it’s put on. It’s a jacket that’s best suited to cold and dry conditions such as mountaineering and skiing trips. Around town, the extra warmth and DWR treatment can make it a clammy experience. In use: This is a well-made technical jacket offering performance for relatively little weight. It’s a delight to pull on at camp or for an alpine start. The DWR treatment held up well in some miserable autumn drizzle. It packs down really well in its own pockets, even though it can be a bit of fight getting it in there. The lack of dry treatment on the down may make it more vulnerable to deflating and clumping in damp conditions. Value: While $650 is a hefty price to pay for any piece of kit, the L3 is a top of the range jacket built for harsh winter conditions. It’s also hardwearing and well constructed – it hasn’t leaked any down in the time I’ve reviewed it – so it should last for many seasons. Verdict: Putting on the L3 downie is a bit like wrapping yourself in an electric blanket: instant warmth. It might not fare so well in more moderate and damp conditions, but if you are after a winter mountaineering jacket the L3 has the chops.