It’s used for detecting the fetal heart rate(FHR) at hospital,clinic,family. Easy to use Without LCD display Built-in speaker Built-in rechargeable battery Specification: Ultrasonic Frequency: 2.5 MHz Dimension: 60(L)x35(W)x130(H)mm Weight : 0.5kg Continuous work time: 8 hours Package:22x17x7cm/unit