Abstract: A mesh screen comprising a pair of rings open at each end. A piece of mesh material is releasably clamped between the rings. The inner face of one cylindrical ring is provided with a circumferential groove and a circumferential flange projecting in the same direction as the mouth of the groove. The inner face of the other cylindrical ring is provided with a circumferential flange which is adapted to mate with the circumferential flange of the first cylindrical ring so that the mesh material may be interposed between the flanges, and the free edge of the circumferential flange of the other cylindrical ring is accommodated within the groove.