... MHZ Features:(1)pocket,hand-hold,use conveniently;(2)Cassette holder for sensor,safety in carry,frame in bend,esily for operation ... ;(4)With data and time or timer function;(5)Ultrasound sensor can be replaced;(6)With inner loudhailer; (7)Better power ... (in option);(9)DSP technology,work frequency in 1MHz or 2 MHz,ultrasound dosage is far less than safe standard of ...