Bunting bags are like small sleeping bags for babies. They have a warm insulated interior and usually a waterproof exterior. Usually, there is an anti-slip layer, too, enabling the bag to stay in place in your stroller. Some bunting bags have an adjustable pull-cord that transforms them into a hoodie, so your child is even more protected from the cold. These bags are also called footmuffs, and they include slots for harness straps, so you can safely restrain your little one.