The Klymit Wild Aspen 0 (Zero) Degree Regular Size Sleeping Bag (Yellow) is thoughtfully designed for four-season comfort. The bag features synthetic insulation for an exceptional warmth-to-weight ratio. The lightweight and durable micro polyester shell is water and abrasion resistant, while the inner liner is designed to retain warmth. The Wild Aspen 0 (Zero) Degree Sleeping Bag features a fully adjustable mummy hood and a built-out foot box for extra comfort. The zipper draft tube ensures the cold air stays out so you sleep soundly all through the night.