Sound level meter can be used for noise engineering, quality control, health prevention and various environmental noise monitoring. Such as: volume measurement applications in various occasions such as engineering, schools, hospitals, shopping malls, cinemas, offices, road traffic, homes, and stereos. The measuring range is 30-130dB With A and C frequency network selection Fast/slow reaction rate selection With maximum locking function With automatic shutdown and non shutdown functions With analog signal output, it can be connected to frequency analyzer or X-Y recorder for data statistical analysis Power supply: 4 xAA batteries (not included) Color: Black & White Material: ABS Package Contents: 1set x noise detectors Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.