Miniature coil intended for custom motorcycles where space is at a premium and single fire is required for maximum performance 3 ohm primary is compatible with Twin Tec Models 1005-1007 and most aftermarket single fire ignitions including Compu-Fire, Crane HI-4, and Dyna 2000 Overall dimensions: 2.4" x 2.3" x 1.6" (not including terminals and tower)