The SL-4035SD is an IEC 61672 Class 2 integrating sound level meter with a 30 to 130 dB auto range, SPL and Leq measurement, peak hold, maximum/minimum recording, and data hold functions. Its built-in SD card real-time datalogger supports selectable sampling intervals from 1 to 3600 seconds and stores measurement data with date and time information for direct computer analysis. It is suitable for factory noise audits, machinery inspection, environmental noise monitoring, building assessment, and occupational safety applications.