This duvet features our luxury down alternative filling, plus a pure cotton percale cover for a refined feel. Its all-season design includes two breathable layers. Choose the 4.5 tog layer for summer sleeping or switch to the 9 tog option for cooler nights. When the coldest weather arrives, you can fasten the pieces together with the handy poppers for 13.5 tog cosiness. It's like having three duvets in one.