Moroso Ultra 40 Plug Wire Set for FXD 28327 All Moroso spark plug wires feature silicone plug boots that withstand high temperatures (up to 600), and have a silicone jacket to reduce heat and chaffing. Locking stainless steel terminals that stay connected under high vibration. Designed to meet or exceed original equipment specifications. Glass center core offers high tensile strength Mesh pull tape provides extra strength