The highest contrast ratio of the Acer 246HL is 100000000:1. That's over five times the contrast ratio of the most frequently found dynamic contrast ratio of 20000000:1.
This LCD screen's contrast ratio (100000000:1) is in fact the best contrast ratio amongst all similar spec LCD screens that have been on the market for more than two years.
Amongst similar types of LCD screen the worst contrast ratio is Mega Contrast.
It may also be worth considering one of the other PC monitors that have a 100000000:1 dynamic contrast ratio currently available including the V236HL ($86.99), or the G237HL ($79.99) both from Acer which has a better Rating.