MSD 37444 Iridium Spark Plug
18mm - .4375 in Reach - Tapered Seat - 4 Pack;Proprietary plug design inside and out; Designed for use on high performance vehicles that utilize high output ignition systems; Machined electrode increases exposure to the flame to improve combustion; MSD’s proprietary ceramic formula provides the highest dielectric strength; Yttrium ground electrode reduces the chance of pre-ignition; Iridium tip improves cold starts; All spark plugs tested prior to packaging and shipping; Unique insulator design improves spark isolation; Lower voltage Requirements for longer coil life;