3M clear bra is the only way to go. Even on a black car you can not tell its there. Its the best I ever had, and when you remove it you have virgin factry paint (ok factory paint sucks!!). A little dirt behind a regular bra will make you sick when you remove the bra.
Here in Colorado they are sold as Clear Bra's. 3M is the manufactor. My Z06 is the third car I have had it installed on. I gave up on the slip ons, because the caused almost as much damage to the paint as they protected. Just my opinion.
The #m material is what is found in the StonGuard and the AutoBahnd products. Had the AutoBahnd product put on my car about 2 months ago and love it. Protects and is not noticeable unless you are right up on the car. Took the installe about 4 hours to apply.
I used a bra that came from one of those corvette parts catalogs,
It had a circular cut out for the emblem on the front and installed
in about 30 minutes. Seemed to fit well and caused no damage
after leaving it on for a few months. It doesn't realy rain here much, so leaving it on seemed to pose no problems. I think for
trips they realy do help keep the nicks and chips to a minimum.