Abstract: An assembly of potted filtering hollow fiber membranes has at least one bundle of permeating hollow fiber membranes that is potted in a block of potting material, and a cushioning wall extending along at least a portion of the axial length of the membranes adjacent the potting material and around at least a portion of the perimeter of the bundle. The cushioning wall can have a fixed edge adjacent the resin, and the wall can extend away from the resin in a direction generally parallel to the axis of the hollow fiber membranes. Walls of various structures including soft solid materials, non-permeating membranes and fabrics are described.