Abstract: The invention relates to a preformed sheet comprising at least two mono-layers, each mono-layer containing unidirectionally oriented fibers having a tensile strength of at least about 1.2 GPa and a tensile modulus of at least 40 GPa, and a binder, with a fibre direction in each mono-layer being rotated with respect to the fibre direction in an adjacent mono-layer, and a separating film on both outer surfaces, characterized in that the separating film has a porosity of between 40 and 90%. With this preformed sheet assemblies and articles offering a substantially higher ballistic protection level at a certain weight can be obtained. The invention further relates to an assembly of at least two such sheets and to a flexible ballistic-resistant article comprising said assembly.