Our model is 10 months old, 30" long and weighs 20 lbs. She is wearing a size medium, sleeveless velour sleep sack with moss green trim. Underneath the sack she is wearing a size medium rib knit footie in moss green. This combination is a great way to keep your baby warm and comfortable during the colder fall and winter months when bedrooms temps. can fall to 61 degrees. This sack is also available with long sleeves.