Abstract: The invention relates to improvements in substrates and in particularly in new substrates having security features which provide security against imitation. A security substrate comprises at least two light transmitting support layers, each having indicia formed by a plurality of opaque regions provided on one surface thereof indicia. The support layers are laminated together with the opaque regions located inside the substrate and separated by at least one layer of an opaque magnetic material of contrasting color to the opaque regions such that in reflected light the indicia are visible. In transmitted light the indicia are not visible.