The white one is for the Mk5 upgrade. Click the AP link I posted earlier in the thread and hover over the white quadrant photo. On there is tells you which is which:
White is post-1995 and more of a semi-circle shape
Black is pre-1995 and less than 1/2 circle.
Originally Posted by SafeChav
you need a black 55mm one.
According to AP site, the black one is 40mm and the white one is 55m radius.
The latest Mk5 Escort Quadrant (white) has an increased radius R55mm over the Pre 1995 Quadrant (black) R40mm.
Either way, you want a BLACK one if you're not doing the mod.