Davies Craig Water Temperature Sensor 1/4" NPT The Davies, Craig ¼" NPT Thermal Sensor Upgrade Kit is designed to fit a ¼ NPT Sensor to Part Number 0444 or 0500 (Digital Thermatic® Fan Switch or Gauge). This will enable you to change the sensor type and fitment options from the 5mm diameter probe sensor provided in these kits as standard. You can use this sensor either as a sparepart for the sensor included in DC-8101, 8102, 8000, 8001, 8002 or as an upgrade to the 5mm probe included in DC-0444 or DC-0500.