Mountain Equipment have two down jackets which utilise lightweight but highly protective Gore Infinium. This version, the Kryos is the warmest with 234g of down and a full feature set designed for harsh conditions.
Mountain Equipment says:
Developed for the cutting edge of Alpine style climbing; the optimum combination of warmth, protection and minimal weight.
Informed by feedback from some of the worlds best Alpinists and extensive R&D work this is the jacket for the hardest and most committing lines in the high mountains. A GORE-TEX INFINIUM drop outer provides proven additional warmth and weather resistance whilst the Super Alpine Hood gives unrivaled protection.
Mountain Equipment's Kryos Down Jacket uses 234g of 800 fill down which provides massive amounts of warmth especially when that heat is sealed in with the Gore-Tex Infinuim outer fabric. This is a serious, cold weather jacket where any sort of exertion could cause you to overheat. The mercury has to drop very far for this to be an all-day garment where you are on the move but for static warmth it works perfectly.
This jacket uses lightweight 10D Gore Infinium fabric to provide windproof and highly water-resistant protection that is ideally suited to harsh conditions where this level of protection is vital. A Super Alpine hood provides excellent coverage and adjustability while the Halo Collar is great for keeping in the heat and keeping out cold draughts. The mixed construction with stitch-through and box-wall baffles maximises warmth while reducing weight and bulk.