All thermal dielectric pads have a Layer Material. Therefore, this layer is not a part of the selection criteria because every standard product offered has such a layer. This table here just makes the distinction between the very common fiberglass reinforcement layer and the polyimide carrier film. These Layer Materials are necessary for this product family because without such a layer the TIM would be very brittle. With a reinforcement or carrier layer, the product remains flexible as well as enhancing other properties such as dielectric strength and cut through resistance.