The R2450SD is a handheld 4-channel thermocouple / 2-channel RTD data logger with a backlit dual-line LCD that displays up to four readings at once, accepts K, J, R, S, E and T type thermocouples plus RTD probes, and logs to a removable SD card (up to 16GB) at intervals from 1 to 3600 seconds so readings export straight to a spreadsheet without extra software. It also offers manual logging of up to 99 points, Data Hold and Max/Min capture, and a wide overall span of roughly -58 to 1700C depending on the probe type used. This NIST variant adds a NIST-traceable calibration certificate for sites that need documented measurement accuracy.