The Chaos Emerald (カオスエメラルド Kaosuemerarudo?), also known as the Chaos Emeralds in Sonic Free Riders, is a recurring Board type Extreme Gear that appears in the Sonic Riders series. It is an exclusive Extreme Gear solely for Sonic the Hedgehog, meaning only he can use it, with the unique ability to transform Sonic into Super Sonic once he has collected a set number of Rings.