Abstract: A neck finish for plastic containers which are closed by plastic caps of the general type having an integral, thin, flexible inward-directed top flange at the lip which initially slants upwardly-inwardly at an angle of about 20.degree.. When the cap is applied, this top flange fits under the top disc of the cap and is depressed to an angle of about 10.degree.. It nests between the outer skirt and the inner skirt. The neck seals against the outer skirt in several locations (as in prior constructions), but the inner edge of the flange seals tightly in the corner where the bottom of the top disc and the outside of the inner skirt intersect. The top flange also augments the sealing effect of the lower edge of the inner skirt and the inside of the neck. Below the cap skirt the container neck has a shoulder to impede any attempt to pry the cap off the container.