Sleepwell Duvets - King 230x218cm This king size Essentials Sleepwell duvet combines a hollow polyester fibre filling with a durable polycotton cover. The hollow polyester fibre filling creates a simple, warming duvet which is perfect for a range of hotels and hospitality settings. Each king size Essentials Sleepwell duvet is machine washable at 40 degrees and the 10.5 tog is ideal for year-round usage.