6638 Ultimate Creatures Accessory Set (Special Edition) is a BIONICLE set released in 2006. It contains 300+ BIONICLE pieces, providing two Kraata jars, several masks, axles, Toa tools, Tohunga feet, Rahkshi masks, Vahki tools, Rahkshi tools, head connector blocks, connectors with ball sockets, rarely it contains a piece from LEGO Sports, etc.