Reflector unit for photoflash array

A reflector unit for a photoflash array, comprising a sheet-like member shaped to provide a plurality of individual reflectors and a plurality of tapered radiation barriers respectively between adjacent individual reflectors, each of said radiation barriers comprising a pair of walls tapering to an apex at the front of the reflector unit, wherein the improvement comprises mutual inward deformation of the pair of walls of one or more radiation barriers in a region at the apex thereof thereby forming one or more ribs in the concavity and near the apex or one of more of said radiation barriers so as to permit nested stacking of a plurality of said reflector units and prevent adjacent reflector units from wedging together.