The North Face Serac Jacket: The North Face Serac was named for house-sized blocks of ice that are formed by colliding crevasses on a glacier. An unstable serac can be dangerous for alpine climbers as it can slide without warning. While this jacket can't protect you from massive chunks of falling ice, its GORE-TEX® Paclite exterior is ideal to wear while mountaineering in such environments. Providing waterproof, breathable, seam sealed protection in a lightweight design; this jacket's elastane fabrication adds a stretch that permits increased flexibility and mobility while reaching with your ice axe for the next hold. Bottom line. Burly.