Arc'teryx Proton SL Hoody (Men's)

The Proton SL is Arc’teryx’s lightest, most breathable insulated hoody—reborn from last year’s Proton Lightweight Hoody with a new name, updated recycled Fortius™ fabric, and cleaner design lines. It keeps the Octa® Loft knit insulation that made the previous version so comfortable and efficient.

This piece is built for motion. The Octa® Loft insulation is warm when you stop, yet dumps heat as you move. The Fortius™ Air 20 shell balances stretch, durability, and airflow, finished with a PFAS-free DWR for light weather resistance. At around 13 ounces, it disappears in your pack but never holds you back.

The cut is trim and layers easily under a shell. A helmet-compatible hood, high-set hand pockets, and a chest pocket make it mountain-friendly without overcomplication.

Who it’s for: high-output athletes who run hot—climbers, alpine scramblers, ski tourers, fast hikers, even cold-weather runners. It’s perfect when you’re pushing hard in cool conditions and need something more than a windbreaker, less than a puffy.

Who it isn’t for: folks who want a big, static belay parka or a weatherproof outer layer. This is active insulation, not your “stand around” jacket.

Where it fits: compared to the Proton Hoody, the SL is lighter, more breathable, and cooler running. It’s the one you grab when movement is constant and overheating is the bigger enemy than the cold.