Two supplementary fins positioned on the rail help to track and guide with their main purpose to provide additional grip in extreme turns. When railing up the board hard, the tail starts to come out of the water, for example during top turns (which then become lip slides) and also in extreme bottom turns. In these extreme situations center or twin-fins may come out of the water but one of the Side Fins will still grip! These Side Fins feature a balanced outline and a straight race curve. They feel more direct and allow more radical turns. Important: The side fins and the covers are made for Mini Tuttle Boxes (MT).