This unit is a solid hub version of the stage 3. The hub is solid 8-rivet and the assembly is heat treated for strength and durability. It is available in a 3, 4 or 6 puck configuration. Use the 3 puck for the lightest option or the 6 puck for the smoothest engagement. The 4 puck is a good compromise for both. Street drivable in 6 puck configuration, but not street friendly due to the rigid hub. OFF ROAD USE ONLY! This setup is intended for track use only.