Yup, I think he meant rotors! Your car has 2 caps & 2 rotors, and they are NOT inexpensive. Further, they are not known to last particularly long on M119.xx motors. How many miles does your car have? Knowing that will help us better opine.

But you probably do need to change them...there's a great article here on the site to guide you through, check the "Do It Yourself" tab at the top of the page.

__________________
"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo