Abstract: A three component coupling assembly consisting essentially of plastic male and female coupling members and an annular seal. The female member has a male fitting engaging end portion formed with interior threads for cooperatively threadedly engaging a threaded male hose fitting. The remaining female coupling portion has a generally cylindrical interior periphery of a smaller diameter size defining at a position adjacent the inner end of the interior threads an annular shoulder. The interior periphery has formed therein a plurality of annularly spaced grooves extending from the outer end thereof through the annular shoulder and a corresponding plurality of correspondingly annularly spaced notches extending from the annular shoulder toward the outer end. The seal has an outer annular portion seaingly engaging an uninterrupted outer sealing surface of the shoulder and an inner annular portion extending over the notches and grooves formed in the shoulder.