Hart Scientific 1523/1524 handheld reference thermometers measure, graph, and record using RTDs, thermocouples, and thermistors with accuracies of up to 0.004%, 0.005%, and 0.01%, respectively. Model 1523 is for single-channel use; Model 1524 is for simultaneous dual-channel use. Model 1524 can log up to 15,000 data points with time-and-date stamp.