LCD Heart Rate Display with signal quality indicator (note that the BT-SOUND version Does not have an LCD display) LCD Display now has a backlight (note that the BT-SOUND version does not have an LCD Display) Low Battery Indicator Heart Rate Range: 50-240 bpm Accuracy ± 2% Ultrasound Frequency 2MHz Ultrasound Intensity 10MW/cm2 Speaker Output Power 1.2W Built-in Loudspeaker Audio output for Earphone Auto Shut Off 5 minutes Auto Shut Off on signal 1 minute Power 1.5V Battery X 2 (Type: AA) Sensitivity From 10 - 12 weeks Battery Life 360 minutes Safety Standards CE Certified, EN ISO 13485: 2003 compliant Conforms to UK and EC Medical Safety Requirements (Medical Directive 93/94/EEC), CE 0470 Show More