The present double layer model belongs to GCS-type models. An essential feature of these models is the decomposition of the double layer into several subregions which are then described as dielectric continua. The author is aware of harsh criticisms on such GCS-type models regarding drastic simplifications of the double layer structure and its parameterization procedure that arbitrariness slips in. Nevertheless, it is undeniable that GCS-type models are simple yet effective in describing physicochemical properties of the double layer.