ACCEL Single/Dual Fire Ignition Systems keep you from having to change modules every time you want to switch from dual-fire to single-fire. Now, all you need to do is flip a switch. You can choose from 14 preprogrammed advance curves that cover everything from a stock Harley to a high-compression race engine. These modules feature machined aluminum housings that double as heat sinks, on-board rev-limiting, and LEDs for easy static timing, and they work with or without vacuum-operated electrical switch input.