Parking Sensor Hole Diameter - 2008 CLK

[E55BOF]

Good afternoon all.

Does anybody know the diameter of the parking sensor holes in the rear bumper for OE parking sensors? I ask because my 2008 CLK has sensor bumpers, with sensors installed, but they are not the original bumpers.

I also need a new head unit, and Pioneer make one that works with Pioneer's own parking sensor kit, which comes with a 19mm hole saw.

 

[E55BOF]

Stop Press - they're not OE at all, they're push-fit from the outside, and they're 21 mm. Either Dolphin, then, or Chinese cheapo-cheapo Dolphin clones.