Simple answer: this is an older screen and it has a simple etched "cross hair," not a microprism focusing aid.
However, I've read a post at photo.net that suggests that the older version is actually brighter than the D version -- but I can't verify that personally.
If you look around enough, you can find a D screen for between $125 - $150, but you have to be patient. Myself, I don't think it's worth the cost (like most Hassie accessories), but that's just me.