Looking for replacement caps for our uniball upper control arms? These are only compatible with our billet or tube uniball upper arms that originally came with caps. You can not retrofit these to work on non-cap version arms as the uniball cup is not machined to accept them. If your arms didn't have caps, do not purchase these. If you're not sure, contact us and we'll point you in the right direction. These cap off the top of the arms to protect the uniball and utilize an O-ring seal. We machine these in-house from 6061-T6 billet aluminum, bead blast them, anodize them black and laser our trademark Camburg logo on them. They come in either bolt-on or press-on styles and come with the necessary O-rings and screws for the bolt-on versions. If you have our X-joint upper control arms, they require different caps. These do not fit our X-joint (ball-joint) upper control arms.