<p>The present invention is directed to a closure having a top wall which has a base cross-sectional thickness, a threaded portion and an annular skirt depending therefrom which includes tamper-evident means frangibly connected thereto. The top wall further comprises a stiffening block from which an inner annular seal and an outer annular seal depend. The inner annular seal is characterized by depending from a point of the stiffening block which is midway between the inner and outer periphery of the stiffening block and which is positioned to sealingly engage the inner wall of the opening of a container to which the closure is applied. The outer annular seal depends from the stiffening block in a manner such that the outer wall of the seal defines the outer periphery of the stiffening block. The stiffening block contains also a groove which defines the point of attachment of the inner wall of the outer seal and the sealing block and a step between the inner and outer seal which impinges the opening of a container to which the closure is affixed. This arrangement provides improved sealing and decoupling of stresses placed on the closure top wall from the sealing means.</p>
