Dosing and mixing cap

A dosing and mixing cap system, comprising:

• a sealing cap body configured to movably engage with the open end of a receiving vessel;
• a product chamber disposed within an interior volume of the sealing cap body and configured to contain a measured quantity of a product composition therein;
• a spacer circumferentially positioned between a proximal end of the product chamber and an interior sidewall of the sealing cap body;
• a selectively displaceable valve configured to form a fluid-tight seal with the spacer to isolate the product composition within the product chamber,
• wherein engagement of the sealing cap body with the receiving vessel causes displacement of the valve relative to the spacer, thereby breaking the fluid-tight seal and permitting the product composition to flow from the product chamber into the receiving vessel.