Abstract: The insert is received within the coupling ring of the faceplate of a two piece ostomy device. The coupling ring has an axially extending rib and a rigid sealing flange defined in part by a radially inwardly extending surface. The insert includes a convex annular body with an arcuate relatively non-deformable portion and a deformable circumferential portion. The deformable portion has an outer edge with a circumference which is normally slightly larger than the inner circumference of the sealing flange. The circumference of the deformable portion is temporarily reduced as the insert passes through the ring. Once the insert is situated under the flange surface, the circumference returns to its normal dimension and the insert is securely seated.