The Rab Men’s Xenair Insulated Vest has the lightweight core warmth required for hiking, climbing, and mountaineering in the alpine during summertime. It features the lightest, loftiest, and most protective synthetic insulation from Primaloft. The Pertex Quantum Air shell offers air-permeable breathability. Unlike standard breathable shells, air-permeable breathability begins to breathe the minute you zip up. The hood fits under climbing and skiing helmets nice and snug. A regular fit lets you layer over baselayers and under rain shells with ease.