Orbit Baby Infant Car Seats sold in the United States can only be used with children who weigh between 4-30 pounds (1.8-13.6 kg), whose height is between 19-32 inches (48-81 cm), whose head is at least 1 inch from the top of the car seat shell, and which can be properly secured in the restraint harness. If you have any questions regarding sizing, please also review all manuals to ensure proper safety.