Clutch Masters 2000 BMW 323I 2.5L E46 7.25in 725 Series Twin-Disc Clutch Kit w/o FlywheelRace (TD7R)2 ceramic rigid discs The Clutch Masters FX725 is a 7. 25" (184mm) Twin Disc clutch and is the ultimate in twin disk performance for engines transmissions with smaller bell housings that are focused on drag racing. Clutch Masters FX725 Twin Disc systems are developed from decades of experience in drag racing. Because of the minimal rotational mass the FX725 isn't ideal for the street but with improvements in friction material over the years