When temperatures are dangerously low and you’re stuck sitting at a belay for 30 minutes, throw the Mammut Men’s Stratus Flash Insulated Jacket on. Made with synthetic insulation and a larger cut, you can throw it on right over your shell to keep that all important heat close to your body. An attached hood fits easily over helmets and chin protection gives your face a place to huddle when the winds kick up. It’s easily compressible, so when you start moving again just stuff it in your pack.