Exemplary embodiments provide bias-able devices for use in electrostato-graphic printing apparatuses using conformable and electrically relaxable rubber materials. The rubber material can include a plurality of nanotubes distributed uniformly and/or spatially-controlled throughout a rubber matrix for providing the rubber material with a uniform mechanical conformability and a uniform electrical resistivity. The rubber material can be used as a functional layer disposed over a conductive substrate such as a conductive core depending on the specific design or engine architecture. Other functional layers can also be disposed over the conductive substrate and/or the rubber material of the bias-able devices including bias charging rolls (BCRs) and bias transfer rolls (BTRs).