725 Series Twin Disc Clutch Kit (15020-TD7R-A) by Clutch Masters®. Includes: Flywheel. Disc Outer Diameter: 7.25". Disc Type: 2 Ceramic Rigid Discs. Flywheel Material: Aluminum. The 725 series is a smaller diameter assembly, which creates less rotating mass and offering quicker, and smoother shifting with much better throttle response, ideal for Drag racing applications.