These illuminance meters provide measurement functions that include illuninance (lx), illuninance difference (lx), illuminance ratio (%), integrated illuminance (lx-h), integration time (h), and average illuminance (lx). Meters feature a silicon photocell receptor that provides highly accurate measurements and includes a USB port for easily downloading measurement data. Use the optional software, part number 50537-09, to import your measurements into Excel® for report generation and analysis. Software sold separately.