The 4 Season® Big Kid Sleep Bag keeps your child at a perfect temperature throughout the night, year-round. That means there's no need to worry about which weight sleeping sack to use, or whether your child will be too hot or cold while sleeping – they'll always be just right! Made with super-fine and supremely breathable merino wool, it helps keep your kid warm when it's cold and cool when it's warm. That temperature regulation means that your child will sleep comfortably throughout the night– and that means a better night's sleep for you too. It comes in a universal size that fits kids from 4 to 6 years. It saves you buying a different sleeping bag for different seasons, as well as buying larger ones as they grow. You just need one Woolino sleep bag for your child that will fit for 2 years.