Ram Clutch 157 Tooth Steel Flywheels are ready to install, right out of the box. Each flywheel is machined from certified materials in house. The SFI certified flywheels are surface ground for a flat, parallel mating surface and balanced to the factory specification within 0.5 ounce inch. Aluminum flywheels feature a 0.25 inch thick steel friction surface for better heat dissipation without distortion that can occur with thinner inserts. RAM flywheels can be resurfaced instead of replacing the insert every time the clutch is freshened. Get the best flywheel first, exclusively from RAM and made in the USA.