Abstract: Electrical apparatus for providing an indication of the level of the contents of a container comprises a temperature sensing unit, means for mounting, e.g. detachably, the temperature sensing unit against a container wall and visual and/or audible indicator means. The temperature sensing unit comprises a temperature sensing circuit including at least two spaced apart temperature sensors and an indicator circuit for energizing the indicator means. In use, energization of the indicator means occurs when the temperature sensors detect at least a minimum temperature difference.