The Windbloc Jacket preserves your body's precious thermal envelope without bulking you out or inhibiting your ability to move freely. To prevent windborne chill, we sandwich a Polartec Wind bloc laminate . between midweight R2 polyester on the surface and a lighter, moisture-wicking R1 grid on the inside. Although the Windbloc is dry and comfortable without a shell, you can easily layer it when a storm moves in. The shoulders are seamless for pack-strap comfort; the handwarmer pockets ride high so they won't interfere with a harness. To further seal out drafts, the wind flap comes up and over the collar, cushioning your neck and chin. With chest pocket, elasticized cuffs and flat-locked seams to reduce bulk.