BDL High Performance Extra Clutch Plate Kit For Harley Big Twin / Sportster Features High performance extra plate kit includes nine aramid fibers friction plates on tempered steel cores and eight tempered steel drive plates Starburst groove pattern for maximum heat dissipation and oil circulation Preset stack height for easy installation 15 more clutch area for high performance strokers 15 more surface area than stock 15 stronger diaphragm spring Made in the USA