Jacket from Arc'teryx. Atom Hoody is a lightweight insulated jacket designed to function as both an outer layer and a midlayer. The jacket uses Coreloft synthetic insulation that retains warmth in damp conditions and features stretch fleece side panels for increased breathability and freedom of movement. The outer fabric provides wind and water resistance, while an adjustable StormHood, zippered pockets and an adjustable hem complete the construction.