Abstract: A coupling including a seal which has an outer periphery that is adapted to be pressed into the inner periphery of a hollow cylindrical sleeve of a gear coupling. An annular flange is integrally attached to the ring and the flange extends radially inwardly and toward and is adapted to underlie the external teeth on the hub of the coupling. The flange terminates in an inwardly directed sealing surface that is adapted to sealingly engage an external cylindrical surface on the hub. The sealing surface on the flange is adapted to be disposed on a plane passing through the center of curvature of the tips of the hub teeth perpendicular to the central axis of the coupling.