Applications and Features& 65306; Widely used in ship, automobile, chemical manufacture, metallurgy, machine, household appliance and many other fields. *It can pick up and amplify the weak audio signals via a sensitive piezoelectric sensor, and distinguish the normal/abnormal signal and its location.  *Desined to help locate the source of excess bearing and machine noise easily at low cost.  *Used to quickly locate the source of engine noise such as piston slap, worn gears and bearings, blown gaskets. Also useful tracking down dashboard rattles and squeaks. Specifications:                Frequency Range                 10Hz~10K Hz                     Input Impedance                 >20M                     Ambient Noise Permitted                 100dB                     Power Supply                 4x1.5V AAA Size(UM-4)Battery                     Dimensions                 156mmx67mmx28 mm                     Weight                 270g(Not Including Batteries)                     Standard Accessories                 Main Unit                     Powerful Rare Earth Magnet                     Sensor                     Probe(Cone)                     Carrying Case                     Manual Book                     Optional Accessories                 Headset         Vibration Standard:       ISO/IS2373 Motor Quality Standard According As Vibration Velocity        Quality Rank    Rev(rpm)    H:high of shaft(mm) Maximum vibration velocity rms(mm/s)        80<H<132    132<H<225    225<H<400        Normal    600~3600    1.8    2.8    4.5        Good(R)    600~1800    0.71    1.12    1.