The baby deedee sleep nest is a quilted wearable duvet blanket for babies 0-36 months. Soft Indian cotton jersey lining and exterior. Designed in a comforting cocoon-like shape to help baby feel cozy and secure, it's the perfect transition from the womb or swaddling stage. Unique shoulder snaps make it easy to place baby into the sleep nest, even while sleeping, in just 2 easy snaps. Small is suitable for babies 0-6 months and 10-18 lb. Medium is suitable for babies 6-18 months and 16-26 lb. Large is suitable for babies 18-36 months and 25-35 lb. Winter weight TOG 2.5. Note-some babies require fewer layers than others, but as a general guideline we recommend using the sleep nest for the specified temperature. For colder rooms in the mid to high sixties, you can dress baby in pajamas and maybe even a body suit under the pajamas. Baby should not feel hot or sweaty when you touch her neck just comfortable