The latency of the 1720B, which uses an LG/Philips LN170E panel, is announced as 16 ms. In practice the results are more like what you see below:

This curve shows the different latency values for different levels of gray. A black-white alternation is shown on the curve by a point with the X-axis 255, a black-gray alternation produces a point at X-axis 125, a black-gray alternation shows as 50, etc.

The official ISO latency rating specified by the manufacturer is only for black/white transitions (0/255). And while the value we measured agrees with the manufacturer's on this point, it's little indication of the responsiveness of the panel in practice. Because in fact latency increased through all the values of gray to attain a maximum of 27.5 ms! This is not an isolated case, and in fact this panel is quite average, with a maximum latency equal to that of the legendary Hydis 20 ms used in our Hercules Prophetview 920 reference monitor. Unfortunately, there are no miracles here; the panel of the 1720B was slower than the Hydis over more than 60% of the use range, which means it's less responsive.