Patent ID: 8727163

Claim:
A lid, comprising: a valve chamber, the valve chamber comprising: a hollow chamber defined by one or more sidewalls having a first opening at a first longitudinal end and a second opening at an opposing, second longitudinal end; a valve flap positioned at least proximate to the second longitudinal end, the valve flap having a shape and size substantially the same as or smaller than a shape and size of the second opening; and a hinge coupling the valve flap to the lid, the hinge sized and configured to enable rotation of the valve flap from an open position to a substantially closed position and to bias the valve flap to the substantially closed position, wherein the valve flap inhibits the flow of liquid through the second opening in the substantially closed position; wherein the lid is a monolithic structure, wherein the lid is shaped and configured to nest with a substantially identical lid with the valve chamber positioned partially within and with the valve flap positioned fully within a valve chamber of the substantially identical lid and with the lid positioned at a parallel orientation to the substantially identical lid.