A dual apparatus having a first unit and a second unit of a same configuration, one being operated in an active state while the other in a standby state. This internal phase comprises electrophoretic particles suspended in a suspending fluid and capable of moving therethrough upon application of an electric field to the electrophoretic medium. The nonwoven web can contain melt-spinnable fibers, such as polyolefins, as well as various other fibers, such as pulp fibers, staple fibers, etc.