Decibel Meter Wall Mounted High Accuracy Battery Level Indication USB 30‑130dB with Alarm Function Sound Level Meter for Bar School Item Type: Wall Mounted Decibel Meter Material: ABS Weight: Approx. 641g / 22.6oz Battery (Built In): Lithium Battery, 1000MAH Product Size: Approx. 23.7x12x2.7cm / 9.3x4.7x1.1in Wall Hole Distance: 8cm / 3.1in Sound Measurement Range: 30-130dB With Maximum Mode, Measurement with Sound Alarm Alert Function, Alarm Value Adjustable Microphone: Digital Microphone Accuracy: ±1.5dB (In Reference Sound Pressure Standard 94dB 1KHa) Frequency Response: 31.5Hz-8.5KHz Digital Display: 3 Inch Digital Pipe Display (10.5 Inch Display) Power Supply: USB Power Supply (DC5V1A Adapter Excluded) Common Problems: Display Doesn't Show (1) USB Cable Is Damaged, Replace The USB Cable; (2) Power Adapter Is Damaged, Replace The Power Adapter; Instrument Maintenance: Cleaning Of The Case: Alcohol, Diluent, Etc. On The Chassis Especially The Windows Have Corrosive Effects, Therefore, When Cleaning, Use A Dryer Wet Cloth To Gently Wipe It. How e: 1. Power button Long press for 3 seconds to turn on or off the power. 2. Add key Press and hold for 3 seconds to turn on or off the alarm function. In voice measurement mode, click to switch between fast and slow speed. 3. Decrease key Press and hold for 3 seconds to turn on the maximum value lock function. In the noise measurement mode, click to switch between A weighted and C weighted. 4. Setting key Press and hold for 3 seconds to enter into the state of setting alarm value, at this time, you can see the corresponding function characters flashing, the number indicates the alarm value, press the increase or decrease key to adjust, press the power button to confirm the exit. Press this key to cancel the alarm. In hold state, press this key to cancel the function. 5. dB Sound Unit Symbol Normal display represents the noise measurement mode. 6. C weighted display symbol When C is displayed, it means C weighted mode (generally used for mechanical noise). No display indicates A weighted mode (generally used for sound that can be felt by the human ear). 7. S slow display symbol When S is displayed, it indicates slow measurement (1 time per second). Not displayed indicates fast measurement (1 time per 250 ms). 8. Maximum value lock function symbol When displayed indicates that the maximum value lockout function is turned on, and only the maximum sound value is displayed at this time. 9. Alarm value on symbol When displayed indicates that the alarm function is turned on. 10. Battery symbol When displayed, it means the built in battery is powered, no display when plugged inB, it means the USB is powered and charging the battery, the built in battery is 1000mAH, it can be used for 8 hours under normal condition.