The Fluke Calibration 561612P Secondary Reference PRT Probe with INFO-CON for 1523/1524, 12 in. x 1/4 in., -200 °C to 420 °C has a temperature range of -200 °C to 420 °C and its high-purity platinum element and durability make it great for calibrating in the lab or in the field.
When choosing a reference with a platinum element, there are two things you want to look at carefully: the short-term repeatability and the long-term drift. When PRTs are thermally cycled over their temperature range as they would be during a calibration, their resistance at the triple point of water can move up and down within an expected range. Fluke Calibration defines this range (called "short-term repeatability") as the repeatability at the triple point of water during three thermal cycles. The 5616-12-P has a short-term repeatability better than ± 0.010 °C. In addition, the drift is ± 0.007 °C at the triple point of water when exposed up to its maximum temperature (420 °C) for 100 hours. These specifications are given at k=2 and therefore include a 95% confidence level.
The Fluke Calibration 5616-12-P has a sealed INCONEL 600 sheath and PTFE-jacketed cable made of silver plated copper that ends with four-wire leads, which eliminate the effects of lead-wire resistance on measurements. Use the 5616-12-P with Fluke Calibration's 1523/1524 Handheld Reference Thermometer, 1560 Black Stack, 1529 Chub-E4, or 1502A Tweener thermometer readouts.
Each sensor comes with a manufacturer's report of calibration. The report includes the expanded uncertainty (k=2) at seven calibration temperature points, ITS-90 calibration coefficients, and a temperature vs. resistance table presented in 1 °C increments.