Features: 100% With 1 equivalent weighted sound pressure level A. A frequency weighting for general sound level measurements. Large LCD screen with digits reading Fast and Slow dynamic characteristic modes. Fast rate to pick up the current reading. Slow rate to pick up the reading of average within 1 second. Maximum value holding function to lock up the maximum reading. Equipped with sponge ball. Auto power off design for energy saving. Low battery indication Portable, easy to use and handy instrument for sound quality control in factory, office, home, school and construction site. product properties: Wild Measurement Range:30-130dB Frequency Range: 31.5Hz to 8.5KHz Linearity Range: 50dB/100dB Digital Display: 4 digits Resolution: 0.1dB Accuracy: +/-1.5dB (under reference conditions) Bar Graph: 50 dB scale at 1 dB step for monitoring current sound pressure level display Overload Indication: OVER/UNDER Frequency Weighting: A Level Ranges: 30-80dB, 50-100dB, 60-110dB, 80-130dB 30-130dB Self Calibration Time: 3sec Sampling Rate: 2 times/seconds Power supply:DC 9V battery Packing content: 1X Digital sound level meter