As we know, even if the screens is original screens, it still has kinds of quality level. Take iphone5/5S for example, there is at least 3 grade. Grade A. No bad pixel, no dust, perfect workmanship, appearance and display effect.( Highly Recommended ) Grade B. second only to Grade A, there are some flaws more or less. For example,1 or 2 tiny bad pixel, or there is a little dust in LCD and so on. But these do not affect use if customer have not strict standard. Grade C. More bad pixel and dust or other some flaws.