The uneven bars or asymmetric bars is an artistic gymnastics apparatus. It is used only by female gymnasts. It is made of a steel frame. The bars are made of fiberglass with wood coating, or less commonly wood. The English abbreviation for the event in gymnastics scoring is UB or AB, and the apparatus and event are often referred to simply as "bars". The bars are placed at different heights and widths, allowing the gymnast to jump from bar to bar.