?High Accuracy?Mastfuyi decibel meter uses a precise condenser microphone to capture sound, measures sound level 30-130 dBA, 35-130dBC. Highly accurate with 1.5 dB, Frequency from 30Hz to 8,000KHz, Perfect for monitoring noise levels in community, home, audio system, automobile, school, office, factory ?A/C Weighted Measurement?When measuring the sound level felt by human beings, select A-Weighting mode which simulates the frequency of low-intensity human ear noise; when measuring the actual sound level like noise analysis of machine motors and machines, select C-Weighting mode which simulates the frequency of high-intensity noises of the human ear. Professional measurement methods provide users with a perfect experience ?Compact and Lightweight?Composite material injection molding process and ergonomic design, non-slip and wear-resistant, comfortable to hold; Slim and lightweight, doesn't take up space, easy to carry and store; Pocket clip design allows it to be securely clipped to the pocket and not easily dropped and lost ?Fast/Slow Measurement?The Fast-Weighting mode uses a constant of 0.125s/time, which is suitable for measuring the sound level in real time in general environment; The Slow-Weighting mode uses a 1s/time constant, which is suitable for environmental measurements with relatively large changes in noise levels ?Versatile Uses?Features a full color LCD screen with a resolution of 0.1 dB, clear and beautiful; MAX hold function to lock the maximum value; Auto power off after 15 minutes inactivity to prolong battery lifespan; Data Hold function to freeze the current readout, easy to read and record data; Flashlight for use at night ?Dual Visual Alerts?Level 1 ( 50dB): ?? analog bar is displayed, no indicator lights up, the acoustic environment is safe; Level 2 (50-90dB): ???? analog bar is displayed and the ?? indicator lights up, better to wear ear muffs or noise-canceling headphones to protect your hearing; Level 3 ( 90dB): ?????? analog bars is displayed, ?? indicator lights up, need to leave the sound source as soon as possible ?Calibration?Before calibrating the instrument you need to prepare a standard sound source device to be used for calibration, please do not calibrate without a standard sound source device. The A-weighted calibration steps are as follows: Step 1: Press SLOW/FAST button, Flashlight/HOLD button and power switch button at the same time and then release the buttons to enter the calibration mode. Step 2: Set the standard source device to 94dB, then align the meter to the standard source device, wait for the meter reading to stabilize at 94dB, press the SLOW/FAST button to save, and then press the power switch button to restart the device that the calibration is complete. The C-weighted calibration steps are as follows: Step 1: Press SLOW/FAST button, Flashlight/HOLD button and power switch button at the same time and then release the buttons to enter the calibration mode. Step 2: Press the A/C button to switch to C-weighted. Step 3: Set the standard source device to 94dB, then align the meter to the standard source device, wait for the meter reading to stabilize at 94dB, press the SLOW/FAST button to save, and then press the power switch button to restart the device that the calibration is complete. ?NOTE?The flashlight can only be used properly when the noise is higher than 50 dB; Turning the flashlight on and off may affect the data hold function ?48-Month Warranty?We provide 48 months unconditional warranty and lifetime after-sales service