Features: 1. 100% brand new and high quality 2. This sound level has instantaneous sound measure function 3. The measurement range is 30-130dB 4. With two equivalent weighted sound pressure levels, A and C 5. Suitable for measuring noise of industrial, environmental and aircraft. Specification: Condition: 100% Brand New Brand: SMART SENSOR Model: AR824 Material: ABS Plastic Digit & Resolution 5 digits & 0.1dB Display: 0.5 secretary Measuring Range: 30~130dBA 35~135dBC Accuracy ±1.5dB Frequency range: 31.5Hz to 8.5K Hz Linearity range: 50dB Frequency weighting: A, C Microphone 1/2 inch Electret Condenser microphone Standard According to IEC651 TYPE 2 & ANSIS1.4 TYPE 2 Time Weighting Fast / Slow Bar graph: 50 dB scale at 1 dB step fro monitoring current sound pressure level display period: 50mS Level ranges: 30-80dB; 50-100dB; 60-110 dB; 80-130dB Over indicate over range: Under indicate less than lower limit for the range AC output: 0.707 Vrms at FS output impedance approx 600Ω DC output: 10mV / dB output impedance approx 100Ω Max: Maximum hold / Auto Power Off Yes External power supply Yes Level Range Bar Graph Yes Range Selection 4 modes Range Over Indication / Battery Indication Yes Backlight Display / Max & Min Hold Function Yes Sampling Frequency 2 times / sec 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 Power 4 * AA1.5 alkaline cells ( battery not include) Weight: Approx. 617g / 21.8oz Size:Approx. 224 * 66 * 33mm / 8.8 * 2.6 * 1.3in Package List: 1 x Sound Level Meter 1 x DC Cable 1 x User Manual .