Features LCD display with backlight, can be used in any illumination conditions. DSP technology is employed to assure accuracy and reliability of FHR detection. High sensitivity probe with 1MHz in pulse(Option: 2.0MHz in continuous)wave. Ergonomic design, portable and convenient. Built-in speaker and sound frequency output port. Automatically power off; Multi-displaying of FHR: number, battery status indicator, voice intensity indicator; Three working modes: Real-time FHR display, Mean FHR display and Manual counting. (Option: 2.0MHz) Specifications FHR Display: LCD display Measurement Range: 50~210 BPM (Option: 30~240BPM of 2.0MHz) Measurement Accuracy: +/-1% or +/- 1BPM LCD Display Dimension 39 x 27mm Speaker power 1W Power Supply: Built-in chargeable nickel-hydrogen battery Working Voltage: 9V Continuous operating time: >5 hours Dimension 330 mm ?30 mm ?0 mm Gross Weight: 0.8 kg Standard accessories One probe, one Gel, one Battery charger