TS AD592 4KV Temperature sensor. This is a custom encapsulation by F&T capacitors Germany. Originally used for motorcycle temperature sensing on dataloggers. The double insulated silicon leads suggests that this item is designed to operate around high voltages i.e an engine head where HT leads / spark plugs are located. The fixing hole is 5.3 mm diameter indicating a M5 bolt. This is not a usual screw in water or oil temperature sensor.