PR-18 series probe with standard aluminum protection head with flip-top includes PT100 ohm platinum RTD element or PT1000 RTD element and 1/2inch NPT mounting threads. This sheath is made of 316 stainless steel. This probe can be used alone or can be placed directly into a thermowell. All probes include a screw terminal block for easy connection of insulated copper extension wire. This probe can be used in tanks, vessels and large pipes for measurement of flow material.