I was thinking the same thing as zip439.
Pull the pads off of the front brakes and take some close up pics.
All of the rotors should be the same as a 2003 Mercedes SLK 320.
I just noticed there is a Brembo part number on the face of the front brake caliper. I can't make it out, but you should be able to.
You can probably go to the Brembo website or contact them with that part number. Then you will know what pads and hardware that you will need.