12mm 40khz receive Ultrasonic Sensor 1. Diameter:12mmSENSOR; 2. Height:9.5mm ... as buzzer(Piezo electric, electromagnetic, mechanical), piezoelectric ceramic element, SMD magnetic transducers, condenser microphones, ultrasonic sensor,Atomization piece ... in household appliances equipment, watches, toys, alarm systems, reversing radar, ultrasonic cleaning, ultrasonic atomization, marine fish exploration, ...