1、100% brand new and high quality. 2、The measurement range is 30 to 130dB 3、It has high/low speed rate selection function, the maximum value holding function and calendar function function, etc. 4、It will auto power off after 10 minutes without operation 5、Suitable for factory, office, traffic road, family and all other noise measurement applications Features: 1. 100% brand new and high quality 2. The measurement range is 30 to 130dB 3. It has high/low speed rate selection function, the maximum value holding function and calendar function function, etc. 4. It will auto power off after 10 minutes without operation 5. Suitable for factory, office, traffic road, family and all other noise measurement applications Specification: Condition: 100% Brand New Brand: SMART SENSOR Model: AR844 Color: White Material: ABS Plastic Measuring Range: 30~130 dBA   35~130 dBC Accuracy ±1.5dB Frequency range: 31.5Hz to 8.5K Hz Resolution 0.1dB Frequency weighting: A and C Digital Display 4 digits Analogy bar graph 1dB or 1 bar graph Sample rate 20 times / second Microphone 1/2inch polarization capacitance microphone Standard According to IEC651 TYPE 2 & ANSIS1.4 TYPE 2 Dynamic range: 50dB/100dB Level ranges: 30-80dB; 50-100dB; 60-110 dB; 80-130dB Overload indication OVER / UNDER AC signal output: 4Vrms/full bar graph, output impedance is about 600 ohm PWM signal output: Duty cycle=0.01xdb value/3.3 x 100% Dynamic characteristic: FAST (high speed)/ SLOW(low speed) Calendar accuracy +-30 seconds/day Data storage quantity 4700 The maximum value holding MAX Auto Power Off Yes (after no operation for 10 minutes) Level Range Bar Graph Yes Range Selection 4 modes Range Over Indication / Battery Indication Yes Backlight Display /  Max & Min Hold Function Yes External power supply Yes Self calibration time: 10 secs(every turn on) Operating condition Temperature :0-40℃; Humidity: 10% to 80%RH Storage Condition Temperature: -10 to 60℃; Humidity: 10% to 70% RH Battery 4 * AA Batteries(not included) Size: Approx. 67 * 30 * 183mm / 2.6 * 1.2 * 7.2in Package List: 1 * Sound Level Meter 1 * DC Cable 1 * USB Cable 1 * CD 1 * Plastic Box 1 * User Manual