Snuggledown Duck Feather & Down duvet is specially constructed using a blend of 85 percent Duck Feather and 15 percent Duck Down; which is then encased in a 230 thread count soft cotton fabric. To keep the fillings in place we use a clever internal box construction which ensures no cold spots develop, keeping your body evenly warm throughout the night. Snuggledown Scandinavian Duck Feather & Down 10.5 Tog All Year Round Duvet in White Size: Double