This cushioned topper has a thick cotton-filled top layer and supportive hollowfibre-filled bottom layer. Layers unzip for washing, and the cotton cover is breathable. Fits mattresses up to 35cm deep. More Sustainably Sourced We always strive to obtain raw materials from more sustainable sources. This product supports cotton farmers who use water efficiently, care for the environment and promote fair and decent work. Temperature Regulating Cotton is naturally temperature regulating and breathable. It keeps the heat in when nights are cold, and lets it out when they're hot. Dual Layer The base layer can stay on the mattress while the top can be removed for washing. A base layer gives support, a top layer adds comfort. Please note: we do not recommend using this mattress topper with an electric blanket as it will significantly limit its effectiveness.