Mile Marker Hub Conversion Kits include 4 nuts and 2 locking rings. They are used to convert automatic hubs to manual locking hubs. Converting to manual locking hubs will allow you to run front locking differentials on the street without the drivability issues normally associated with them, resulting in better fuel economy. Stainless steel construction provides strength and corrosion resistance. These kits are ideal for enhancing and protecting your vehicles drive train system in order to withstand the rigors of everyday use.