Abstract: An indicator is provided for a heating unit which may be used as a soft contact lens disinfecting unit and which embodies an exterior construction entirely of thermoplastic material. Wax contained in the unit is used as a heat transfer medium, as a temperature stabilization means, as a heat sotrage medium, and, in accordance with the present invention, as a unique indicator system which enables the user to confirm when the unit has reached the proper operating temperature. The heating unit to be described, is specifically constructed to produce or aid in disinfecting so-called soft contact lenses intended for wearing in contact with the eye. The unit is more generally applicable, and may be used to advantage, when a low cost heating unit is desired which will raise the temperature of an object or a material to a given temperature, maintain it at or above the given temperature for a given time period, and then allow it to cool down and return to an ambient temperature condition.