... quality,low price,fast delivery Good folding strength High stiffness duplex paper board with gray back1) A and AB grade, ... produce 250gsm,300gsm,350gsm,400gsm, 450gsm and 500gsm paperboard with grey/white back. 2) Consistent quality 3) High stiffness, ... excellent print fidelity 4) No deformation5) No picking in full page printing6) Good folding strength, no cracking after corrugated lamination7) ...