These are a pair of brushed aluminum caps that are 1/2" thick with a 3/8" deep pocket 2 1/2" diameter in the backside for clearance for the dust cap on the front rims. These could be run on the front or back, but we do sell the thinner sets if you want that front to back staggered look. The hole centers are 2 1/8" pattern, this will fit many different rims.