How warm? Very warm. How comfortable? Very comfortable. Smartwool's Men's Smartloft 120 Jacket uses 88% recycled wool insulation for lightweight, packable warmth and breathability even when wet. It also features a DWR-coated nylon shell for protection and a wool lining for sweat and odor management. It fits perfectly into any winter adventure.. . Main: 100% Nylon. Trim: 48% Merino Wool/44% Polyester/8% Elastane. Lining: 56% Merino Wool/44% Polyester. Fill: 88% Wool/12% Polyester. 120g proprietary recycled wool insulation offers lightweight, packable warmth, breathability, and insulation even when wet. Wind-resistant nylon with DWR protects from the elements. Insulation is lined in Merino for sweat and odor management. Stretchy knit panels target Merino next to skin and polyester against the elements while allowing for ease of movement. Zip chest pocket with cord routing and zip hand pockets. Imported.