1358 Sound Level Tester Digital Decibel Meter Noise Tester for Factory School Airport Office Item Type: Digital Decibel Meter Model: 1358 Material: ABS Battery: 1 x 9V 6F22 (Battery Not Included) Uses: Widely used in noise measurement, quality control, health prevention and various environmental sound measurement, such as residential area, industrial and mining factory area, school, office building, airport, transportation, waiting hall and other scenes. Measuring Range 30~130dBA, 35~130dBC Accuracy ±1.5dB (under reference conditions) Frequency Range 31.5Hz~8kHz Grade Range 30~80,50~100,60~110,80~130,30~130dB Frequency Weighting A/C Digital Display 4 digits Accuracy 0.1dB Sampling Rate 2 times/sec Bar Graph Displayed as 0-30 dB: One scale unit represents 2dB For Other Levels: one scale unit represents 1 dB Excessive Signs OVER/ UNDER AC Output 0.707Vrms at FS output impedance is about 600Ω DC Output 10 mV / dB, output impedance is about 100Ω Time Quality fast/slow Microphone 1/2 inch electret condenser microphone Maximum Maximum Battery Life About 30 hours Self Calibration Time 3s Operating Condition 0~40℃,10~80%RH Storage Condition  -10~60℃,10~70%RH