Extech-SDL400-Light-Meter-&-Data-Logger-EXTECH-SDL400-The-Extech-SDL400-light-meter-with-data-logger-records-data-on-an-SD-card-in-Microsoft-Excel-reg-format-for-easy-transfer-to-a-PC-for-analysis-The-user-can-manually-store-99-readings-or-set-the-logger-to-automatically-store-up-to-20M-samples-with-date-&-time-stamp-at-a-user-selected-sample-rate-The-meter-uses-a-precision-silicon-photo-diode-&-spectral-response-filter-to-give-a-wide-range-of-cosine-&-colour-corrected-measurements