This is the crank trigger wheel only. Below is information on completed crank trigger kits. Upgrading to an MSD Flying Magnet Crank Trigger Kit will deliver the precise and reliable signal that a high performance engine requires. Gives you the ability to control timing electronically through a Holley EFI ECU (or other standalone engine management system / ignition controller). At the heart of the kit is the 3-wire Hall-Effect Sensor that is easier to set up, less susceptible to EMI/RFI interference/noise, and less likely to have false signals than other methods (Distributors and VR Magnetic Sensors). In addition, they are less prone to mechanical failure since there are no wear parts. With the included high quality timing pointer and the use of a direct bolt-on, degreed balancer (see below list for recommendations), you'll be able to adjust timing in the precise increments required for your engine. • Coyote 556-173 We recommend using ATI 918047-MSD but will also work with 918047N and 918047NA • LS 8 inch 556-174 Designed to work directly with ATI 917302, 918852, 917264 or 917242 • LS 7.28 inch 556-175 Designed to work directly with ATI 917777, 917211 or 917234 • LS 6.56 inch 556-176 Designed to work directly with ATI 917776 or 917215