Built for 4,000-meter peaks, it’s ready for use at all frigid altitudes and in the harshest mountain conditions. This weatherproof down jacket offers ultimate Mammut cold protection in its lightweight, compressible form. This is made possible by the durable recycled nylon exterior with its 850 cuin fill power derived from responsibly sourced hydrophobic down that insulates even in wet conditions. The backpack and harness compatible pockets can be used for your essentials when you’re hiking or belaying, and you can even stow the jacket inside if you need a little extra warmth.