This is a new Currie Jeep JK Wrangler rear disc brake rotor for use with our semi-floating JK rearend units. These rotors are most commonly sold when a customer who buys our JK bolt-in rearend package, intending to use the factory brakes, would like to purchase new rotors that have already been drilled with both 5 on 5" and 5 on 5 1/2" wheel bolt patterns for 1/2" studs. For a pair of rotors, 2 of this part number would need to be purchased.