... 4. Advanced power management system. Longer-lasting battery life.5. Silicone Rubber Keypad. Operating feel good6. Multi-frequency ... histogram statistics, frame correlation.8.Upgrade depth : Multi-file real-time to upgrade7.Measurement: distance, perimeter, area, volume, heart ... .Character display: Real-time clock, date, name, gender, age, gain, hospital name, probe type and the operating frequency, full ...