24 Jul Transducer Ultrasonic 25khz 4 pieces MK-109C 349 25 DIA X 20 MM dog collar frequ
HELLO EBAYERS , UP FOR "BUY IT NOW " ARE ULTRASONIC TRANSDUCERS MADE BY MASSA ,,, THESE ARE NEW OLD STOCK NOT USED,, YOU ARE BUYING IT NOW FOR 4 PCS,,, FREE GROUND SHIPPING IN USA . WE DON'T KNOW WHAT THE FREQUENCY IS FOR...