... to be installed on the bike’s spoke.Features:Fit on bike with a wheel diameter of 20″ or greater WaterproofShuts ... on the front or back wheelDisplays Time Riding:Displays Wheel Rotations Display sequence: Message, Patterns, Time of Riding, Number of Rounds, ... either side of your wheel, because if the letters are backwards, you can change the letter intofrontwards easily by hold the ON button ...