Purchase instructions: 1.The product is powered by USB cable, please confirm before purchase, you have USB socket applicable Product has no battery, it uses AC power supply 2.Usually in a very quiet room, the value will not be lower than 40dB, which is normal. Description: Large digital LCD display Measurement range is 30 ~ 130dB The indicator light blinks and buzzer Alarm Use the device to measure noises inside or outside. With hanging holes, can be hangged on the wall DC 5V 1A Type-C USB power supply Product size:22.8cm*12.5cm*3.2cm ?8.96in*4.91in*1.26in Specifications: Model: SW-525A Measurement range : 30 ~ 130dB (dB) Accuracy: +1.5 dB (reference sound pressure level, 94dB @ 1kHz) Frequency response: 31.5Hz ~ 8.5kHz frequency weighting: A Response time: Fast Microphone: 6mm condenser microphone Power supply: DC 5V 1A Type-C USB working environment: 0 - 40 degrees (32 degrees Fahrenheit to 104 degrees Fahrenheit), 10 - 80%RH Storage of Temp. and humidity: -10~60C. 10~70%RH Package Included: 1 x SW-525A sound level meter 1 x USB cable? 1 x Manual Brand: TestHelper Large Screen LCD Display