6.75" Small Block Ford Super Duty Blower Balancer for High Boost Applications. Meets & exceeds SFI 18.1 specification featuring an all aluminum case design for light weight, stress-proof steel hub and 1040 steel inertia rings for durability. Wet clutch friction design style with precision machined harmonic dampening for street and race engines.Comes standard with 6-bolt (Dual) BBC Bolt Pattern and blower hub option.