Feature: LCD display with backlight, can be used in any illumination conditions High sensitivity probe with 2.0 MHz in continuous wave Accurate and reliable FHR detection with clear sound Ergonomic design, portable and convenience Built-in speaker Automatically power off Multi-displaying of FHR: number, battery status indicator, voice intensity indicator Building-in rechargeable battery and AC recharger. Specification: LCD Display Dimension 39x27mm Speaker power: 1 W Power Supply Built-in rechargeable battery DC, Working voltage: 7.4V, Li-ion battery Continuous operating time: > 5 hours AC recharger Ultrasound Frequency: 2.0MHz continual wave Intensity: