features: 1. digital there channel ecg machine; 2. simultaneous 12 leads acquisition; 3. multiple operation mode (manual /auto); 4. self-test upon powering on; 5. designed with a high-resolution thermal printer to print out ecg waveform, annotation as well related parameters for diagnosis reference; 6. digital isolation technology is adopted to minimize time/temperature drift of components so as promote adaptability of the unit to circumstance; 7. digital filter for effective inhabitation of baseline drift, interference, as well automatic position of baseline; 8. function of rhythem lead for observing abnormal ecg waveform and heart rate; 9. automatic measurement and interpretation of ecg waveform to relieve doctors from strain; 10. multiple print formats include 3-channel, 2-channel, 1-channel and particularly the one that combines 3- channel (for lead 1-avf) and 2-channel (for v1-v6); 11. ac/rechargeable battery for supporting continuous examination when ac power supply is unavailable; 12. for battery operation, ecg-903 is equipped with a charger and system for battery capacity management and protection itself from excessive discharge; 13. safety level corresponds to class i, type cf.