Engine Harmonic BalancerFluidampr Adapter HubHarmonic Balancer Adapter Hub - Big Block Chevy - EachHarmonic Balancer Adapter Hub - Fluidampr - Big Block Chevy - EachHarmonic Balncr Hubharmonic, Balancer, balancer, hub adapter, fluidamprProper press fit for optimum Fluidampr performance damper effectiveness is 0.001 +/- .0005. If press fit is compromised from repeated removal and installation, a replacement Fluidampr adapter hub is recommended to maintain performance. Fits Fluidampr 800101 & 82050E, Chevy 396-427ci internal balance.