A dosing cap comprising: a collar member having an annular skirt depending from a base, an inner surface of the annular skirt having a securing member for securing the collar member to a neck of a flexible container; the base having: (i) a top surface and a bottom surface, (ii) a valve seat on the top surface, the valve seat having a center channel, and a radial channel, the channels (36, 38) extending through the base; a plug member composed of a polymeric material, the plug member having the following components in inter-connected relationship a head, a body, a leg, an ankle, and a foot; the leg extends through the center channel, such that the head opposes the valve seat on the top surface and the foot opposes the bottom surface of the base; a cap member having an annular sidewall extending from a dispensing element, an inner surface of the annular sidewall having an attachment member adjustably attached to a reciprocal attachment member on an outer surface of the skirt; a metering chamber formed by an enclosed volume between the cap member and the base; and the dispensing element permitting flow of a fluid from the metering chamber, wherein the plug member is moveable between: an open position where the plug member permits fluid flow through the channels (36, 38); and a closed position wherein the flexible foot imparts a closed biasing force against the bottom surface of the base thereby: (i) forcing the head onto the radial channel to seal the radial channel; and (ii) forcing the body onto the center channel to seal the center channel. a collar member having an annular skirt depending from a base, an inner surface of the annular skirt having a securing member for securing the collar member to a neck of a flexible container; the base having: (i) a top surface and a bottom surface, (ii) a valve seat on the top surface, the valve seat having a center channel, and a radial channel, the channels (36, 38) extending through the base; (i) a top surface and a bottom surface, (ii) a valve seat on the top surface, the valve seat having a center channel, and a radial channel, the channels (36, 38) extending through the base; a plug member composed of a polymeric material, the plug member having the following components in inter-connected relationship a head, a body, a leg, an ankle, and a foot; the leg extends through the center channel, such that the head opposes the valve seat on the top surface and the foot opposes the bottom surface of the base; a cap member having an annular sidewall extending from a dispensing element, an inner surface of the annular sidewall having an attachment member adjustably attached to a reciprocal attachment member on an outer surface of the skirt; a metering chamber formed by an enclosed volume between the cap member and the base; and the dispensing element permitting flow of a fluid from the metering chamber, an open position where the plug member permits fluid flow through the channels (36, 38); and a closed position wherein the flexible foot imparts a closed biasing force against the bottom surface of the base thereby: (i) forcing the head onto the radial channel to seal the radial channel; and (ii) forcing the body onto the center channel to seal the center channel. (i) forcing the head onto the radial channel to seal the radial channel; and (ii) forcing the body onto the center channel to seal the center channel.