48-Month Warranty : We provide 48 months unconditional warranty and lifetime after-sales service. ?Compact and Portable?As small as a pen and weighing only 1.76 oz, easy to carry and store; Pocket clip design allows it to be securely clipped in the pocket, on the notebook, etc., and not easily dropped and lost; Pen-style design ensures that the noise meter fits comfortably in the hand, and the non-slip design on the sides and back ensures that the decibel meter is easy to hold and resistant to falling ?Wide Ranges, High Accuracy?Mastfuyi decibel meter uses a precise electret condenser microphone to capture sound, measures sound level 30 dB to130 dB. It's calibrated at factory, with highly accurate with 1.5 dB, frequency from 31.5Hz to 8KHz. Widely applicable for monitoring noise levels in communities, home theaters, audio systems, automobiles, workshops, schools, offices, factories ?Fast and Slow Measurement?The SPL has the function of converting the fast and slow response rate, more specialized features for a wider range of uses. In FAST mode, the sensor samples the signal 8 times per second, which is suitable for measuring transient noise or instantaneous changes in noise; in SLOW mode it samples 1 time/s, which is suitable for continuous noise measurements, and indicate the average level of fluctuating noise ?Multifunction?MAX lock function to continually record the highest measurements during the sampling time, easy to read and record data; A low battery indicator will appear on the screen when the battery is low to remind the user to replace batteries in time; Sound level indicator illuminates green when below 60 dB and red when above 60 dB as a visual alert ?A Weighted Measurement?This noise meter contains A-weighting to simulate the frequency of low-intensity human ear noise, it is more accurate and professional for the detection of environmental noise ?48-Month Warranty?We provide 48 months unconditional warranty and lifetime after-sales service ?Calibration?Step 1: Press SLOW/FAST button and power switch button at the same time, press and hold SLOW/FAST button and don't release it, after power on, press the power switch button briefly, the screen shows MAX to indicate that it enters the calibration mode. Step 2: Set the standard signal source device to 94dB, then align the meter to the standard signal source device, wait for the meter reading to stabilize at 94dB, press the SLOW/FAST button to save, and then press the Power On/Off button to restart the device, the calibration is completed