Disclosed herein are aspects and embodiments of an apparatus for securing hollow fiber filtration membranes in a filtration module. In one example, the apparatus comprises a restraining structure engaging elongate portions of the plurality of hollow porous membrane fibers and an anchor formation engaging the plurality of hollow porous membrane fibers and positioned closer to eye portions of the plurality of hollow porous membrane fibers than at least a portion of the restraining structure. Neither the anchor formation nor the restraining structure sealingly engage open ends of the plurality of hollow porous membrane fibers.