The Ptarmigan Tent Insulation is a packable, easy-to-install, synthetic insulation system for the Sparrow and Sparrow XL tents. Extend the comfort range of your Roofnest and stay warm in the winter! The Large size insulation fits the 2020 Sparrow XL (56″ wide version). The extra large size fits the new 2021 Sparrow XL (60" wide version). Please note that because our Sparrow models have changed over the years, this insulation system may need to be adapted to your Roofnest if you purchased your tent before Summer of 2020.