Ingeniously designed, the Smartwool Smartloft Jacket features a, well, smart blend of fabrics that mix and match wool, synthetic, and stretchy materials to maximize our comfort. This includes a wind-resistant and water-repellent nylon shell up front to shed the elements with a stretchy polyester-wool blend in the arms, sides, and back for more mobility, breathability, and moisture control when we work up a sweat. Smartwool also lined the torso with wool and polyester fill for insulation that keeps us warm in both dry and wet weather. Not to mention, the insulation includes recycled wool for a smart performance that's also eco-friendly.