A ferromagnetic shielding funnel for reception within the conical portion of a cathode ray tube having support members at the corner portions of its wider end. The support members project over a small distance into the inner space of the funnel for forming reference faces. The funnel has indentations so that, when two funnels are stacked one upon the other, the indentations in the lower funnel receive the inwardly projecting portions of the support members of the upper funnel, so that damage during and after stacking is prevented.