Chris Townsend reviews an unusual down jacket, breathable enough to be used as a midlayer in the coldest conditions.

This review is part of our down jackets gear guide, and was first published in the January 2019 issue of The Great Outdoors.

This is a very unusual jacket, designed as a highly breathable midlayer not an outer layer. The shell isn’t windproof, which it is in every other down jacket as it must be tightly woven to keep the down from coming through the fabric. There is no loose down in the Aonach. Instead, it is fused with polyester to make a sheet of material known as ThinDown. Berghaus says ThinDown is 30% warmer, more compressible and far more durable than 100% polyester. The soft stretch shell is claimed to have 50% times the airflow of downproof fabrics.

No baffles are needed with ThinDown, however there are some stitch lines as the garment has body mapping (thinner areas where maximum warmth isn’t needed). Features are standard, with hand-warmer pockets and a stretch hood, cuffs and hem. The pockets are cut off by a hipbelt. The hood isn’t adjustable but you need a shell when it’s windy anyway.

I’ve found the Aonach very comfortable and warm. Breathability is excellent. As a warm midlayer for the coldest conditions it’s excellent but it doesn’t have the versatility of a standard down jacket.