Technical parameters: 1. Display mode: liquid crystal display screen. 2. Measuring mode:depressurization type oscillometric method for measurement. 3. Power supply: Tow AAA alkaline batteries (3V). 4. Measurement range: (20-280)mmHg / (2.7-3.7) kPa (blood pressure) / (40-160) times/min (pulse rate). 5. Accuracy: ±3mmHg / ±0.4kPa (blood pressure) / ±5%（pulse rate). 6. Air charging mode: Automatic charging. 7. Air leakage device: Air relief valve. 8. Quick air leakage : Electronic air release valve. 9. Result display: High pressure/low pressure/pulse. 10. Unit conversion: Conversion of blood pressure value unit mm Hg/KPa (default unit when start is mmHg). 11. Number of memory groups: Double 99 memory groups. 12. Low battery inspection: LCD displays symbol "battery" to indicate low battery. 13. WHO tip: Blood pressure warning strip is used to indicate blood pressure and health status. 14. Arrhythmia tip: LCD displays "♥" flickering to indicate arrhythmia. 15. Overpressure protective function: Automatically releases air when air pressure exceeds 295mmHg(20MS). 16. Automatic shutdown function: Automatic shutdown in one minute when there is no operation. 17. Current: Dynamic current less than 500mA , statistic current less than 30 mA, shutdown current less than 20uA. 18. Normal working conditions: a) Environment temperature: 5-40 degrees Celsius. b) Relative humidity: Less than or equal to 80%RH. c) Atmospheric pressure: 85kPa ~ 105kPa. Set speaker sound: Press the Set button, it will show "SP ON" on screen, it means the spearker sound is switched on. Press the Set button, the display will be changed to "SP OFF". It means the speaker sound is switched off.