The highest contrast ratio of the Acer 236HL is 100000000:1. That's over five times the contrast ratio of a 20000000:1 PC monitor, which is the most common contrast ratio.
This PC display's contrast ratio (100000000:1) is actually the best contrast ratio across all similar spec PC screens that have been on the market for around the same time as the 236HL.
A Mega Contrast dynamic contrast ratio is the worst contrast ratio amongst similar types of PC display.
Other PC displays that have a 100000000:1 dynamic contrast ratio currently available that you might want to consider include the V236HL (£124.74), or the B236HL (£139.98) both from Acer which has a better Rating.