xfyred:
Yes, just go to any MB dealers and give them the part number. It should be around $7-$8.

Dan Root:
Each spring has 1 pad. So changing from 21mm to 5mm will give you approximately 16mm drop. However, in the case of Mercedes, every single car comes with different spring pad settings. It's hard to generalize that every crossfire will have certain pad setting. This is why when I lower my C36 AMG versus some of my friend, even tough we both uses the exact same H&R, our drops looks different because we are using different spring pads. The thinner the pad is, the firmer your ride will be.