I used a heat gun to to open my headlight, I do not recommend anyone to open the headlights by this method, takes a lot of time, and make it really hard to re seal it.
these are the rings that I have
http://www.ebay.com/itm/BMW-Z4-E85-E...ht_2807wt_1189
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2005 z4 2.5i/// Aero front bumper, m rear bumper,08 rear lights, custom quad exhaust, matte black front grill, OEM alarm, llumar security film,m wheels, HID lights, LED interior and trunk light,Ipod integration, stubby antenna,tein s-tech springsx