The warmest option in the Atom series performs as a standalone or midlayer. Atom Series: Synthetic insulated midlayers. Excellent used condition no flaws I can see! Only wore half season and not that much, this jacket is super warm more thicker than my other atom jackets maybe it’s thicker version not sure but it’s an amazing jacket for layering or stand alone Features: Technical Features Moisture-resistant outer face fabric, Breathable, Lightweight, Compressible and packable, Insulated Wind resistant Construction Light, durable and wind resistant Tyono™ 30 has a dura coating for increased longevity, Resilient Coreloft™ synthetic insulation is mapped for optimal thermal performance, Permeair™ 20 underarm improves breathability Cuff & Sleeves Configuration Stretch-woven cuffs, Cuff construction increases durability, eases layering and removal Design & Fit Regular fit ensures optimal ventilation with comfort and mobility Fabric Treatment DWR (Durable Water Repellent) finish repels moisture Hem Configuration Drop back hem, Adjustable hem drawcord Hood Configuration Insulated helmet compatible StormHood™ with structured mini hood brim P ocket Configuration Two hand pockets with hidden zippers, Internal chest pocket with zip