Significantly improve your engine's Acceleration and deceleration with this lightweight flex plate. This American-made flex plate is the lightest flex plate available anywhere. It is S.F.I. 29.1 certified and tested to 12500 RPM. This 153-tooth internal balance flex plate fits Small Block Chevy & Big Block Chevy with 2 piece rear main seal. Zinc-plated steel will protect the flex plate against corrosion. Other applications are available.