to the base to provide means for control of the effective rate of volatilization or evaporation of the active material such cover or closure member commonly may be positively locked with respect to the base as shown in fig1 to prevent unintended evaporation or volatilization of the active material after opening of the closure member to expose the contained gel the cover may be adjusted relative to the base to permit substantial control or variation of the rate of volatilization of the gel said base and cover may preferably be of a molded plastic material although other materials may be utilized the container may further comprise support members or posts around which the gel member is molded or formed which members or posts which may be singular or plural provide support and strength to the gel material in the container the gel materials to which the present invention applies are well known to practitioners of the art as are the methods of manufacture and positioning in a container such as shown in fig1 and need not be discussed in greater detail for the purpose of this invention the provision of active or volatile materials and the choice thereof for the purposes of the dispensing devices of this invention are also well known and as such need not be discussed further rather the present invention is directed to the relationship of the dimensions of.