Our product has unique electronic compression depth and frequency detector.
1. First right operation: the 4 indicate light on the left shoulder will be on.
2. the lights off: lack of battery or operation mistake
3. when start the operation, yellow and green light will be off
3. red light: Press frequency 0-60 beats/min
Yellow light: Press frequency 60-80 beats/min
Green light: Press frequency 80-100 beats/min
1)right operation: 2 green lights on Press frequency >100 beats/min
2)red light flashing:compression depth insufficient