Angel Eye Projector Vacuum-control?

Hello,

I have just purchased a Xenon Angel Eye headlight for my SLK R170.
I know how to set them up, except one little detail:

Where do I need to place the little purple tube, for the vacuum controlled adjustment? Or these don't have this feature?

If you need pictures, just ask, though as far as I have seen, they are standard Angel Eye headlights, found on eBay.

P.S. The back of it is the same as in this picture:
http://www.benzworld.org/forums/att...r-halo-angel-eye-headlights-lp-mbslk98-yd.jpg

Thanks!