Abstract: A ring filter comprising a star-shaped folded filtering material and a closure on both front sides thereof in the form of a closed end disc. This closure has a plate-shaped insert forming the central area of the closure and located radially inside the filtering material. The insert is made of a different material from that of the rest of the closure. The invention aims at providing a ring filter than can be rationally produced and that is more resistant and durable. To this end, the ring filter has a radially permeable tubular frame that extends approximately along the entire axial length of the ring filter that borders radially inward on the filtering material; and wherein the plate-shaped insert is connected to the tubular frame and wherein the material of the closure is a foamed plastic.