The FX400/HDCL (8-puck) ceramic full face disc design creates a quick and rapid engagement and maintains minimal chatter due to the marcel cushion between the disc linings. This disc is designed for street driven vehicles.The FX400/HDC6 (6-Puck) ceramic paddle design creates a quick and rapid engagement as well as clutch chatter that may not be ideal for street driven vehicles. Warning Due to the solid (no Marcel) friction rivet design, the FX400 6 disc engages very quickly and may chatter slightly in first and reverse. To help alleviate this problem, we only use premium ceramic friction material.