A duplex board is a sheet of double-ply paper, similar to the kind of thick paper used to make cards. Duplex board is often used in packaging and has a distinctly smooth, almost waxy feel.
Bristol Karton: Solid bleached sulphate (SBS) is a virgin fibre grade of paperboard. This grade is made purely from bleached chemical pulp and usually has a mineral or synthetic pigment coated top surface in one or more layers (C1S) and often also a coating on the reverse side (C2S). It is a medium density board with good printing properties for graphical and packaging end uses and is perfectly white both inside and out. Its other properties, such as being hygienic and pure with no smell and taste, make it usable for packaging aroma and flavor sensitive products such as chocolate, cigarettes and cosmetics.