The highest contrast ratio of the Hanns.G HS241 is 80000000:1. That's over four times the contrast ratio of a 20000000:1 flatpanel monitor, which is the most common contrast ratio. The best contrast ratio of all LCD screens of a similar type and age to the HS241 is 100000000:1 and the worst is Mega Contrast.
We think you might also be interested in some of the alternative PC displays that have an 80000000:1 dynamic contrast ratio currently available including the HL226 (£89.99), or the HS221 (£89.98) both from Hanns.G or the Asus VS239 (£115.50) which has a better Rating.
If you want an LCD screen with a higher contrast ratio then you might want to consider the Asus VN279 (£119.99) (100000000:1 and higher rated), or the Acer V236HL (£124.74) (100000000:1 and higher rated).