High Performance Extra Plate Kit - 1998 Big- Twin & Twin Cam models thru present. Includes 10 Kevlar® friction plates on 6061 T6 aluminum cores, 9 tempered steel drive plates and a 10% stronger than stock diaphragm spring. Pre-measured stack height for easy, accurate installation. Perfect for Hot Street or Strokers! 11% MORE SURFACE AREA THAN STOCK. Includes performance diaphragm clutch spring.Stack Height: Frictions and steels 1.840 - 1.855"