Ear tags are plastic or metal objects used to identify livestock and other animals. If the ear tag uses RFID technology, it is called an electronic ear tag. The electronic ear mark complies with the international standards ISO 11784 and ISO 11785 (134.2 kHz operating frequency) and ISO / IEC 18000-6c (UHF operating frequency). There are other non-standard systems, such as destroyers, that operate at 125kHz.