If you want a very stable thermometer from –200 °C to 670 °C and are particular about the calibration, then look no further than the 5609 Secondary Reference PRT. Its short-term stability at the triple point of water is only ± 7 mK and its one-quarter inch (6.23mm) diameter lets you get accurate measurements in only 100 mm of immersion. P (INFO-CON for 1523 or 1524) 300 mm x 6 mm -200 to 670 °C lead wire (cable) 6 ft