... good stiffness, strength,good folding strength 3.for printing 1.duplex board with grey back from 230gsm to 500gsm, 2. wiyh good ... stiffness, strength,good folding strength 3.for printing packing 4. duplex board with grey back is suitable for 4-8 color printing ... , and many kinds of bag, box package, etc.5. The duplex board with grey back can be producted according to the customers ...