SCREW CAP

A screw cap for containers with a threaded neck portion, comprising: a base portion comprising a top surface and a bottom surface, the bottom surface having a center, and an annular portion raised from the base portion. The annular portion has an inner surface and an outer surface. A threaded portion is arranged on the inner surface of the annular portion, the threaded portion having at least one thread, the thread extending from a start into a first circumferential direction around the inner surface, the start being that part of the thread, where the material of which the thread is made, starts to rise from the inner surface. An engagement portion is arranged on the bottom surface and projects from the bottom surface, the engagement portion having a reference line that runs along the bottom surface and crosses the center, whereby all material that makes up the engagement portion is arranged on one side of the reference line, the reference line touching at least one point of material that makes up the engagement portion, and whereby the angle between a plane that contains the center and the start and is orientated perpendicular to the bottom surface and the reference line is larger than 0° and smaller than 30°.