United Kingdom Flyball League (UKFL) uses a patented ulna measuring device, measuring the distance between the 'elbow' and bone of the stopper pad with a minimum height of 6 inches (15 cm) and a maximum of 12 inches (25 cm). Current EFC (European Flyball Championship) rules limit the height to no less than 17.5 cm and no greater than 35 cm. Each dog must return its ball all the way across the start line before the next dog crosses. Ideal running is nose-to-nose at the start line. The first team to have all four dogs cross the finish line error free wins the heat. Penalties are applied to teams if the ball is dropped or if the next relay dog is released early.