PREMIUM FABRICS FOR BEST COMFORT - The award-winning 4 Season® Ultimate Baby Sleep Bag keeps your baby 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 baby will be too hot or cold while sleeping – they’ll always be just right! SAFER, BETTER, AND LONGER SLEEP - Made with super-fine and supremely breathable merino wool, it helps keep your baby warm when it’s cold and cool when it’s warm. That temperature regulation means that your baby will sleep comfortably throughout the night– and that means a better night's sleep for you too. Cuddly-soft organic cotton outer adds to the comfort as it's perfect for the most delicate skin. THE ONLY SLEEP BAG YOU NEED - It comes in a universal size that fits babies from 2 months to 2 years. So, instead of 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 baby, right up until they turn two!