Abstract: A threaded lid for closing the opening in a pump housing having a body portion and a gripping formation defined by a ridge on the body portion having a central portion and projections extending beyond the central portion. A juncture between the central portion and each of the projections varies gradually from a rounded angle at one terminus of the juncture to a gently sloping ramp at the other terminus of the juncture, so that a simple elongated tool such as a stick may be placed between the projections of the gripping formation and rotated to loosen the lid, but not to tighten it. Furthermore, the mildly curved S-shape provides surfaces which conform to the hand to enable substantial manual loosening force to be applied comfortably to the lid, whereas the surfaces of the gripping formation engaged by the hand to tighten the lid are not conducive to the application of a substantial amount of manual force.