This is a new product that is simple to fit to the back of any riding jacket; simply sew 2 x 15mm black buttons (supplied) to the back of the jacket and the number holder just buttons on, ending the need for messy string and torn numbers. The holders have been made to a size of which allows them to sit comfortably on the rider's back and allows the use of most sizes of number. They are not waterproof but they will protect the number in the event of rain.