This may be the only jacket that you'll find irreplaceable. The Arc'teryx Atom LT Jacket is and has remained a favorite among the Arc'teryx line because of it's usability in every situation. Use the Atom LT as a mid layer for a massive boost in warmth, or an outer layer in light rain. PolartecR Power StretchR with HardfaceR Technology keeps movement fluid with it's 4 way stretch properties and a DWR finish keeps moisture from penetrating through. The real secret to the Atom LT is 60 grams of CoreloftTM Insulation, a highly packable and weightless filling with immense warming power and quick drying properties. A jacket for tackling life with premium comfort and protection, the Arc'teryx Atom LT Jacket is as good as they get.