The north face men's thermoball full zip jacket is a compressible synthetic jacket for staying warm in cold, wet conditions. the thermoball comes in at under 13 ounces and stows into its own hand pocket, hardly noticeable in your bag, but packs a warm and toasty punch when the temps drop. each little square baffle has been filled with thermoplus™ insulation, and while it is synthetic, it mimics down. that means it's super lightweight, compressible, but with the added advantage of staying warm when wet. whenever you're heading into the backcountry, grab this little wonder for loads of warmth.