Mattress enhancer: Get an all natural 5cm duck feather mattress enhancer. Cover: Made with a 100% cotton percale cover. Sizes: Option of a single, double, king or super king. Straps: Designed with four elastic straps to ensure it fits easily around your mattress. Filling: Sumptuously filled with white 100% duck feathers. 5cm deep: Box stitch for an even distribution of filling.