All four costumes are size 3 to 4. The mermaid costume is size 100 which is around at 3T American. It is new with tags and has never been worn. The Disney aerial skirt is missing the top, but it is also a size 3. Both have elastic waist and are stretchy. I believe the brand for the other three is Jakks pacific size 3 to 4. light signs wear on the costumes.