Hays steel flywheels are manufactured from certified billet material that will not break up under the stress of high RPM and severe punishment of racing. This 30 pound flywheel fits the SBC, BBC with 2 piece rear main seal and has 153 tooth ring gear. The flywheel is drilled for 10.5 in Borg & Beck or diaphragm style pressure plates. Internal engine balance. Bolts included. Other weights and applications available.