These keep the center link from rotating under hard 4wd launches. Replacing the factory idler arm with our billet, dual ball bearing unit will eliminate the centerlink from rolling just like the pitman and idler support brackets but without the bending and shearing of the heim joint nuts that have been an issue in the past. This is the solid and bulletproof way to ensure your centerlink will not rotate and no more worn out pitman and idler arms. It is a solid billet piece with Dark Gray Sparkle powdercoating. Fully rebuildable! Includes a nylock nut.