The Ultimate Low-Profile Insulation Layer The Arc'teryx Men’s Atom SL Jacket (Hoodless) is a precision tool for thermal regulation, designed specifically for those who prefer a streamlined, non-restrictive collar. By removing the hood, this version of the Atom SL becomes the ideal mid-layer for high-speed mountain activities, fitting perfectly under a hardshell or a heavier insulated piece without creating a "bundle" around the neck. It is built for "SL" (Superlight) performance, offering just enough warmth to take the edge off a chilly alpine start or a breezy ridge line while ensuring you don't overheat once the heart rate climbs.

The jacket utilizes a hybrid construction: the core is protected by a thin layer of Coreloft™ Compact insulation to maintain body temperature, while the side panels are made of breathable stretch fleece for rapid moisture transport and heat release. The Tyono™ 20 shell fabric provides a surprisingly durable barrier against the wind, treated with a DWR finish to repel light mist. Sleek, packable, and incredibly light, this jacket is a staple for climbers, hikers, and cyclists who need versatile protection in a compact package.

Key Features:

• Zonal Coreloft™ Compact 40: Lightweight insulation is concentrated in the chest and back to protect the core while maximizing packability and breathability.

• Hoodless Mid-Height Collar: A soft-lined, streamlined collar provides wind protection for the neck without interfering with other layers or helmet straps.

• Tyono™ 20 Shell: A premium, air-permeable fabric that balances wind resistance with the airflow needed for high-intensity movement.

• Stretch Fleece Side Panels: High-stretch panels under the arms and along the torso provide a trim fit and excellent ventilation.

• DWR (Durable Water Repellent) Finish: Helps shed light moisture and prevents the face fabric from wetting out during misty conditions.

• Uninsulated Mesh-Lined Sleeves: Provides comfortable next-to-skin feel and light wind protection without adding bulk or excess heat to the arms.

• No Slip Zip™: Specialized zipper tracks prevent the main zip from accidentally sliding down during active use.