This sleep sack has an ultra soft and cozy hand feel outer with a soft polyester filling and is perfect for autumn and winter use. The generous sack design allows room for kicking but cannot be kicked off so baby stays warm all night. This is a very warm winter model baby sleep sack for room temperatures below a certain level and the recommended nursery temperatures should be between a cool range. A baby sleep sack surrounds the baby providing insulation from both below and above and also a warm pocket of air around the baby. Baby sleep sack should be sleeveless to aid heat loss and air circulation and babies sleeping under traditional blankets rarely sleep with their arms inside and the sleeveless design reduces the risk of overheating. It unzips from the top which makes it easy to place baby in the sack and unzips from the bottom which makes it convenient for diaper changing and with zipper protectors on the back and at the end it protects baby from scratches.