There are two types of Combination Core construction. The first type consists of a center veneer core and a crossband veneer on both sides of the center with a layer of MDF, particleboard, or hardboard under the face and back veneer. The second type consists of an oriented strand board or wafer board center with a veneer crossband on both sides, under the face and back veneer. Combination Core can be used when the project calls for consistent flatness and good screw-hold ability, without the weight of a MDF or particleboard core.