For Sportster rear 1979-later. Use pre-1992 hardware. Flat head allen kit #E5986. Left side, 11 1/2 inch O.D., 2 inch I.D.These brake discs are CNC machined from a special ductile iron alloy that is superior to stainless steel.For Sportster rear 1979-later. Use pre-1992 hardware. Flat head allen kit #E5986. Left side, 11 1/2 inch O.D., 2 inch I.D.These brake discs are CNC machined from a special ductile iron alloy that is superior to stainless steel. When used in conjuction with GMA or OEM style calipers, a dramatic improvement in stopping power is experienced. These discs provide increased friction coefficiency, high heat capacity with warp resistant qualities, excellent wear characteristics and a grooved pad surface that decreases gas buildup under hard braking conditions and evacuates water for instant stopping power in bad weather. Manufacturer