The Testo 0628 0006 NTC (negative temperature coefficient) thermistor immersion probe measures temperature from -35 to +80 degrees C (-31 to +180 degrees F). Its probe measures 40mm (1.57") and has a 3mm (0.12") diameter tip. It has a response time of 5 seconds in water for fast readings. The probe is Ingress Protection certified IP67 for protection against dust and short periods of immersion in water. A 1.5m (5') cable connects the probe to the unit.