These are used for setting up your upper axle link of the front or rear of your rig, The ID mounting surface is 2 5/8" for a standard 1 1/4" rod end with misalignments. These are made out of 1/4" thick material with a 9/16" hole so you can drill them out to a larger diameter if needed. They have 3 different locations to adjust to.
Sold individually