All the thermometers are metal sheathed and both less fragile. True Standard Platinum Resistance Thermometers.
Thermometers use hand-made coil wound platinum sensing elements to give high accuracy and low drift.
SPRT. Temperature Range: -200°C to 670°C
Model 670 Standard Platinum Resistance Thermometer construction permits the four
internal platinum lead wires to expand and contract in the same manner as those of
Temperature range from -196°C to 670°C.
Semi-standard PRTs are typically made in stainless steel sheaths which are
6mm in diameter, and have an Ro value of 100 ohms and an alpha [(R100-Ro)/Ro]