Features: Maximum locked. Clock and calendar functions. Background light in the night work. Appropriate recognition rate selection: fast / slow Measuring range from 30dB to 130dB and automatic range. With two equivalent weighted sound pressure level, A, and C. Instrument in accordance with IEC651 2 type, ANSI S1.4 2 designs. AC and DC output analog signal, which can be linked to a frequency analyzer or XY axis recorder.