The Mammut Men's Eigerjoch Advanced IN Hooded Jacket would've been the envy of every old-timer to ascend the Eiger back in the day. This insulating jacket is packed with the power of 850-fill down for a level of warmth that any mountain climber dreams about, and Primaloft Gold Active covers the hood, back, and sleeve ends with insulation that stays warm when wet. Once the snow clears up, if you're feeling toasty, simply stuff it into its stuff sack that's disguised as a chest pocket.