The 6 mm transmitter is the latest addition to Thelma Biotel’s tag range. With a diameter of only 6.3 mm, it’s our smallest tag yet and possibly the world’s smallest tag in the frequency range of 63-77 kHz. With a more than 35% volume reduction, the 6 mm tag maintains nearly the same transmit range and battery life as the classic 7 mm tag, allowing for more flexibility when tagging small fish.