US Patent 7465881 Coupler stem assembly

The present invention relates to a coupler stem assembly including a coupler and a stem, the coupler includes a polymer material that has been molded to a predetermined shape, an outer surface that is threaded and provided with a coupler axis, and an inner surface that defines a cavity and that includes a retaining member, the stem includes an outer stem surface that is provided with a stem axis and that is shaped to fit within the cavity defined by the inner surface of the coupler; and a retaining surface that is located on the outer stem surface and shaped to cooperate with the retaining member of the inner surface of the coupler.