... 2. coated with caolin and wood pulp 3. good printing duplex paper board with gray back High quality,low price,fast ... delivery Good folding strength High stiffness duplex paper board with gray back1) A and AB grade, can ... produce 250gsm,300gsm,350gsm,400gsm, 450gsm and 500gsm paperboard with grey/white back. 2) Consistent quality 3) High stiffness, excellent print ...