"This is not an OEM gear replacement; rather it is an aftermarket high performance direct replacement gear set. It is made using the same process as the gears for NASCAR. The gears are made from 8620 steel (USA made steel), and are in-house heat treated both before (for a better granular structure) and after forging. Each family of ring and pinion gears has a specific heat treatment recipe (i.e. the Ford 8.8 is different than the 230mm Nissan). After forging, the gears are turned. In order to reduce the chance of nicks and dings, the threads are turned last and then "drawn back on the pinion gear" (heat tempered). This strengthens the threads on the pinion gear so that the nut will fail before the gear. Each ring and pinion is "run-in and lapped"(mated exclusively to each other), ensuring that each ring and pinion sets up properly. Each set is then hand engraved and identifiable as a unique set; one ring gear precisely mates only to one pinion gear."