Assembly comprising a wide-mouth plastic preform or container having a reinforced neck finish and a screwable closure

An assembly comprising plastic preform or container and a removable closure that can be screwed onto the plastic preform or container, wherein the plastic preform or container comprises a hollow body and a neck finish terminated by a wide-mouth opening, the neck finish comprising a neck support ring and a neck portion extending between the wide-mouth opening and the neck support ring, wherein the neck portion has a height and is provided with a thread for screwing the removable closure onto the neck portion, and comprises an upper portion and a reinforced lower portion, wherein the upper portion is extending between the wide-mouth opening and the reinforced lower portion, wherein the reinforced lower portion is extending between the upper portion and the neck support ring, wherein an inner face of the reinforced lower portion is transitioning to an inner face of the upper portion along a transition step in such a way that the reinforced lower portion is thicker than the upper portion at least in a top part of the reinforced lower portion, wherein the assembly includes (i) a junction between a top end of the transition step and the inner face of the upper portion that is concave and defines an inward transition radius, and (ii) a junction between a bottom end of the transition step and the inner face of the reinforced lower portion that is convex and defines an outward transition radius, and wherein the removable closure comprises a deformable sealing material, and when the removable closure is screwed onto the neck finish of the preform or container, the neck support ring is disposed below the removable closure and the upper portion of the neck portion is in contact with the deformable sealing material, and a seal is achieved only between the upper portion of the neck portion and the removable closure.