Constructed with ultralight 100% nylon ripstop Pertex Quantum fabric and filled with 850-fill-power sustainably-sourced Traceable Down, the 850 model is a lightweight 3-season mummy bag and features Patagonia’s expedition-proven center-zip design. Weight is just 32 ounces. Rated to 19ºF it is available in short, regular & long lengths for perfect fit & maximum comfort.