STEELMAN 06802 Decibel Meter for EngineEAR II Stethoscope 7 switchable control settings that range from 60 decibels to 120 decibels Equipped with ultrasensitive piezoelectric microphone and removable metal probe accessory Easily accessible standard sized 3.5mm jack for use with the headphones of your choice Built in LED low battery indicator Uses an easily replaceable 9V battery (not included)