Abstract: A unitary packing especially suitable for use in pumps which transport liquids such as water-based solutions or suspensions includes a generally concave working face having an outer cylindrical annular flange, a generally convex opposed face preshaped for complementary overlying engagement with the working side of a pump piston. The packing, during use, is characterized by substantially reduced stresses and an extended life when compared with conventional packings. The packing may also be structured for occasional axial rotation with respect to the cylinder wall of the pump, which rotation may be enhanced by providing a force-directing element on the concave working face of the packing, this occasional rotation serving to circumferentially reorient the outer cylindrical annular flange of the packing with respect to the inner wall of the pump cylinder to thereby uniformly distribute wear caused by imperfections such as occlusions in the cylinder lining.