Emits a tone at 100 beats per minute
Helps rescuers apply chest compressions at the ideal rate and rhythm.

Warns of rescuer fatigue
The audible tone ensures that rescuers are aware if they are slowing down due to fatigue – a common cause of ineffective CPR.

Reprogrammable tone rate
Can be reprogrammed to 60 beats per minute if desired but the European Resuscitation Council and the American Heart Association recommend 100 beats per minute.