Crocs' shoes were originally designed for people who enjoy water sports, designing "a pair of shoes that are waterproof, non-slip and will not leave shoe marks on the board." The shoes were made from a natural gum using a special patent and became an instant success. After being launched, it was favored by American celebrities and became popular all over the world. It was sold in 40 markets around the world, with a monthly production volume of four million pairs, and the revenue alone was US$354 million.