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 ball container can be filled with ink of the desired colour.

Each 0.5-litre fill is enough to mark 25-30 cows.

When a cow is properly in season she will receive very clearly identifiable back markings from the bull wearing the device.

Marks fade in 4 to 14 days.