Abstract: A one-piece closure for sealing a container having a neck portion includes a top wall (2) connected with a substantially cylindrical side wall (3) and an annular seal (24) that extends downwardly from an inner surface of the closure. The side wall (3) has a substantially contact wall thickness and the annular seal (24) is deformable, in use, on application of the closure to the neck portion of a container such that it at least in part abuts the side wall (3). A tamper evident ring (40) separates from the closure at substantially the same time the annular seal (24) disengages from the neck portion (5).