This thermal probe gives your Ultra Power battery charger the ability to monitor battery temperature during charging. When the user preset temperature is reached the charger cancels the charge cycle. This safety feature can prevent fires as well as prevent battery damage.
As you can see from the pictures above, the probe is comprised of a length of cable with a JR style plug and a plastic case that encloses the thermistor probe. The plastic case can be removed exposing the bare thermistor. The case has two bar magnets inside which are intended to hold the probe to the side of metal cased cylindrical cells. Removing the case allows you to tuck the thermistor into much smaller areas or tape it, velcro it, to the side of the battery.