Maybe just my model is broken, or at least the temperature is only displayed once shortly after you have inserted the batteries, then it will turn off and can not turn it back on, the "ON" button is useless here. That it is up to the batteries can not be, I've tried it with others. Anyway, it does what it is, it measures the temperature, have in this case measured the water temperature.
Other convenient features include the suction cups, so you can attach the device to the wall temporarily.
Conclusion: Unfortunately, a gross defect when the unit would remain on, I would give 5 stars.
