1, For ultrasonic beauty cavitiaton machine ( lost weight , slimming), 2, 28, 33, 40, 50 Khz 3, ... Has drive circuit drive them Our ultrasonic transducers are used for ... Ultrasonic lost weight machine , thin face and other ultrasonic beauty machine . Frequency : 28Khz, 33Khz, 40Khz, 50W ...