The present invention relates to a convex shell for use in a base plate of an ostomy appliance. The convex shell (1) comprises an annular ring (5) defined by an outer edge (6) and an inner edge (7) defining a through-going hole (8). The annular ring has a higher flexibility around a first axis which is perpendicular to the centre axis of the through-going hole relative to the flexibility around a second axis having an angle to the first axis and being perpendicular to the centre axis of the through-going hole.
