The Chin-Ball Mating Harness was developed in New Zealand, and is used around the world for identifying mated cows. The robust harness/halter has a cone-shaped device underneath which contains a freely-rotating ball, working on the same principle as a ball-pen. The stainless-steel container can be filled with ink of the desired colour. Each fill is enough to mark 25-30 cows (approx. 0.5 litre). When a cow is properly in season she will receive very clearly identifiable back markings from the bull (or cow) wearing the device. Marks fade in 4 to 14 days. We suggest changing colours on a 3 week cycle, to prevent any confusion. Ink is available in 1 litre containers. Ink is oil based. NB: Ink must be mixed thoroughly if it has been stored for some time.