Blinkers are usually made of leather or plastic cups placed on either side of a horse's eyes - attached either to a bridle or to an independent hood. Blinkers that have a peep hole cut in the back of the cup are known as visors.[2] Many racehorse trainers believe that blinkers keep horses focused on what is in front, encouraging them to pay attention to the race rather than to distractions such as crowds. Additionally, driving horses commonly wear blinkers to keep them from being distracted or spooked, especially on crowded city streets.