The ST1 is a general purpose probe utilising a thermistor sensor. This is contained in a stainless steel sheath of 4.8mm nominal outside diameter, 125mm long, which is, in turn, connected to a two core cable, 5m long. Thermistor type - 2000 Ohms at 25 degrees C. Accuracy over a temperature range of 0 to 70 deg C +/- 0.2 deg C with a 6 second response. Sensor can be buried in the soil or exposed for air temperature measurements.