The highest contrast ratio of the Acer B246HYL is 100000000:1. That's over five times the contrast ratio of a 20000000:1 flatpanel monitor, which is the most common contrast ratio.
This PC monitor's contrast ratio (100000000:1) is actually the best contrast ratio amongst all medium monitors that are a similar age to the B246HYL.
The worst contrast ratio across comparable types of PC monitor is Mega Contrast.
There are a number of alternative PC displays that have a 100000000:1 dynamic contrast ratio currently available that you might also want to look at including because of it's better review score, the 276HUL, or the H276HL (£239.99) both from Acer.