4-wire set. Includes one 34" 90coil 135plug + one 30.5" 90 coil PC plug (front) + one 18" 90coil 135plug + one 17.25" 90coil PC plug (rear). Ready to install spark plug cable set with a Spiro-Pro core with .409" Pro Race (10.44mm) diameter cables that feature a spiral wound core with 350 Ohm/ft. resistance for excellent EMI and RFI suppression. With a 3-layer silicone technique consisting of a 10.4" an 8" and a pure silicone inner core. Layers are separated with a heat treated fiberglass woven mesh below the first layer and a fiberglass braid below the second layer for pull strength. Offers 600 (315) continues heat protection. The plug boot is 100% pure silicone around a double spring locking terminal for a positive and vibration resistant connection to the spark plug. Note: Compatible with all Harley ignitions. If you have an aftermarket ignition please check with manufacturer ohm requirement. For very high ohm ratings you can use Taylors Carbon Core wire sets. For magnetos and point ignitions Taylors metallic core wire sets are recommended. 18-23 M8 Softail