Competition Clutch Ultra Lightweight Steel Flywheels (STU suffix) are recommended for forced induction and/or track and rally racing applications. This flywheel is machined with less material to assist in quicker revving capabilities. Well-suited for Stage 3 and up clutch applications. Made of 4140 forged steel and are a one-piece design. All flywheels are SFI certified. Not all applications have the ST and STU versions available. Flywheel weights vary from 8lbs to 18lbs depending on application. Flywheel: Steel: Ultra Light: 2002-06 Acura RSX, 02-05 Honda Civic 2.0L 5-Speed: 11.00lb Acura: RSX 02 - 06 2 L Engine, Honda: Civic 02 - 05 2 L Engine