These springs are a bit longer than the normal Spyder valve springs. If you plan to tune or tweek your MR or AMG, you'll not find any replacements in any existing aftermarket spring kit to date. You can cut and stretch these till you get the tuning results you want or simply use them as a replacement spring for old worn out ones with no more resilience.
This is a replacement for Kingman part #10C in your manual.
