Baby GAP jumpsuit. The inside is fleece-lined, so I think it's quite warm. There's no fleece lining in the arm area, but the upper body, legs, and even the feet are fleece-lined! The sleeves can be flipped over to form mittens, perfect for keeping warm! Actually, my daughter wore this when we went on a snowboarding trip to the snowy mountains when she was 1 year and 2 months old(^^) I think she only wore it during that trip. There are no noticeable stains, so you can still wear it!! You can use it for snowy mountains, playing in the snow, or for taking your child to and from daycare in the cold season. Thank you for looking.