Found these by chance on the Crocs Japan website. They're only available in childrens at current. From what I can gather, Mammoth is a Japanese cartoon character & Crocs brought these out for it. Instead of Duke the Crocodile on the rivet, it's the Mammoth logo which is a rainbow with a mammoth - guess this is why there is a rainbow on the front! Not sure if they're coming over here or of the price etc. as they were only released onto the website on 16th June '07!!!