Worn as a midlayer or standalone, the Cerium has emerged as a go-to for virtually any alpine undertaking. Seeking to take it higher, Arc'teryxrefined the design and sourced more sustainable materials while maintaining its exceptional warmth-to-weight ratio and packability. Responsibly-sourced 850 fill down - with Coreloft synthetic utilized in areas prone to moisture - provides premium insulation. The outer - recycled 15D Arato nylon - is light and durable, a bio-derived liner reduces petroleum use, and the insulated StormHood extends the warmth.