Sleet, snow, cold. That's the kind of weather the Penzum thrives in. This versatile insulated with a durable ripstop nylon shell sheds drizzle and shuns wind. It houses the lofty, very warm-for-its-weight, PrimaLoft Gold insulation, a compressible synthetic that holds the warmth it collects, even if it gets wet. Quilted at shoulders and side seams (areas of high abrasion from pack straps and belts) while the rest is smooth for maximum warmth.