The temperature/series is designated by the first digit following the dash in the part number. e.g. 600-series is STTC/SMTC-0xxx, 700-series is STTC/SMTC-1xxx and 800-series is STTC/SMTC-8xxx. The 600-series for light load or low temperature applications, 800-series for high temperature and thermally demanding applications.