Everyone should have a heavy down coat they can pack in their bag if they are winter backpacking or sumitting peaks in the winter. This Salewa Ortles Medium 2 is their medium weight coat, but it is full on heavy winter coat that provides an immense amount of warmth if you are asking me. Featuring good cuffs that keep cold and snow out, a waist cinch and a full coverage hood that will fit over a helmet.
And it packs down reasonably small, larger than a Nalgene. But I put it in the bottom of my day pack on winter adventures above treeline. You should get this coat if you do things in the cold.
Salewa says: https://www.salewa.com/en-us/ortles-medium-2-down-mens-jacket-00-0000027161
The Ortles Medium 2 Down Jacket is a warm insulation layer for alpine mountaineering that combines duvet warmth with minimal pack size. Whether used as an insulating mid layer or as an outer layer, the 3D box chamber construction, 750 cuin 90/10 Responsible Down Standard duck down fill and TirolWool® Celliant® hybrid insulation inserts are positioned specifically to provide the right amount of heat retention required by different parts of the body. TirolWool® Celliant® also continues to keep you warm even when it is wet, which is why we use it at the hood, shoulders and cuffs. The lightweight, abrasion-resistant nylon ripstop outer fabric is ideal for alpine use. With a tailored, rear-adjustable hood and high collar for maximum storm protection. Featuring our free motion patterning and ergonomic sleeves and shoulders to prevent hem-lift while climbing. Packs down small into its compression stow bag.