Captain Creative Super Sponges are the highest quality sponges in the World! They are made of real cellulose sponge material. These 3" numbers are one inch thick and are perfect for learning numbers and beginning math concepts. The colors of the sponges may vary from pack to pack. These sponges are not meant for children under the age of 3 years old. We recommend adult supervision for kids under the age of 6 years old. Perfect for sponge painting and water play.