These skid plates are steel plates to assure very long wear life. black oxide to prevent rust.
it is advised that you replace the skid plates when they have worn down to about 1 mm thick.
this will greatly increase the life of the chassis and will bring you back to the origional thickness of the stock settings.
NOTE;
If you shoe goo these plates in place when new, it will keep them in place when you have to remove the diff case for maintainence.
IT IS ALSO ADVISED THAT YOU USE A NEW BUMPER. PART NO. MUGEN E0410
It is important to note that these skid plates fit flush to the bottom of the chassis and will not effect the droop settings and cause you to scrub speed on the landings.