Abstract: A flexible diaphragm with a U-shaped surrounding fold, containing a plurality of reinforcing fabric members of cross-shaped configuration cut from an elastomer or other suitably coated sheet of material of woven fabric in which the threads are in right-angled relation, each of the cut members having outwardly tapered arms extending from a central area, the cross-shaped configuration having an orientation with respect to the threads of the fabric such that the right-angled threads will extend longitudinally and transversely of each arm, in which the cross-shaped members are stacked in superimposed axial relation with the radiating arms of adjacent cut members being successively offset and having their edges in overlapped relation, and wherein the stacked cut members are encased within a molded elastomeric or other suitable material.