A controlled release container comprising: a base including a flexible diaphragm , the diaphragm includes an outer portion surrounding an inner portion , the outer portion extends generally from a standing surface of the container to a hinge radius (118; 118A, 118B) between the outer portion and the inner portion , a longitudinal axis (A) of the container extends through a center of the inner portion; wherein the container is of unitary construction; and wherein the container is formed by blow-molding; characterized in that : the inner portion of the diaphragm includes a button portion adjacent a first portion of the hinge radius and a hinge portion adjacent a second portion of the hinge radius , the first portion has a smaller radius of curvature than the second portion ; the button portion protrudes further from the base than the hinge portion , the button portion is offset from the longitudinal axis (A) and is between the longitudinal axis (A) and the first portion of the hinge radius , the hinge portion is between the longitudinal axis (A) and the second portion of the hinge radius ; the hinge portion is generally linear and the button portion has a relaxed convex radius when in a relaxed initial position, upon being depressed by a user the button portion is configured to move from the relaxed convex radius to a depressed concave shape as viewed fiom an exterior of the base; when moved to the depressed concave shape the flexible diaphragm reduces an interior volume of the container to dispense a dosage amount of material stored within the container, the dosage amount directly corresponds to an internal volume of the container displaced by depressing the flexible diaphragm; wherein the button portion includes a first thickness (Tb) that is less than a second thickness (Th) of the hinge portion , the container includes a sidewall having a third thickness (Tw) that is greater than both the first and the second thicknesses (Tb, Th), and the second thickness (Th) is greater than the first thickness (Tb) and less than the third thickness (Tw). the inner portion of the diaphragm includes a button portion adjacent a first portion of the hinge radius and a hinge portion adjacent a second portion of the hinge radius , the first portion has a smaller radius of curvature than the second portion ; the button portion protrudes further from the base than the hinge portion , the button portion is offset from the longitudinal axis (A) and is between the longitudinal axis (A) and the first portion of the hinge radius , the hinge portion is between the longitudinal axis (A) and the second portion of the hinge radius ; the hinge portion is generally linear and the button portion has a relaxed convex radius when in a relaxed initial position, upon being depressed by a user the button portion is configured to move from the relaxed convex radius to a depressed concave shape as viewed fiom an exterior of the base; when moved to the depressed concave shape the flexible diaphragm reduces an interior volume of the container to dispense a dosage amount of material stored within the container, the dosage amount directly corresponds to an internal volume of the container displaced by depressing the flexible diaphragm; wherein the button portion includes a first thickness (Tb) that is less than a second thickness (Th) of the hinge portion , the container includes a sidewall having a third thickness (Tw) that is greater than both the first and the second thicknesses (Tb, Th), and the second thickness (Th) is greater than the first thickness (Tb) and less than the third thickness (Tw). <EOS>