The 528 starts to kick things up a serious notch. It measures custom colors, like customer logos and spot colors. It includes a digital version of the Pantone library of colors, built in, which means the Pantone colors never drift or fade, unlike the familiar color charts and chips. It also allows you to compare and match colors between color sample or ink drawdown and the printed product. The 504, 508, and 518 cannot do this. This is the minimum device I recommend for a flexo pressroom. 3-year warranty