Our Lightweight Flexplates are: SFI 29.1 certified Quality HSLA 60 grade steel Tested to 12,500 RPM Lightest flexplate available anywhere Manufactured in the USA Zinc plated for corrosion protection 60.1 lb.-in.2 moment of inertial - 51% of the moment of inertia of an equivalent typical OEM flexplate. Significantly improves your engine acceleration and deceleration *** MOUNT BALANCE PLATE BETWEEN THE FLEXPLATE-FLYWHEEL AND DRIVE HUB ***