Designed to be the highest output GM style HEI in-cap coil, Period. Engineered with enhanced, low resistance, low inductance, high-turns ratio windings around an M36 high silicone magnetic steel core which allows the coil to be charged faster for more energy at high RPMs, and no loss of energy at idle. Compatible with both original HEI ignition systems and later model computer controlled HEI systems. Can also work with an ACCEL, Mallory, Crane, Holley or MSD capacitive discharge ignition system. No need to remove or re-time distributor. Special high temperature, high density epoxy resists even the unforgiving shock, vibration and high temperatures of street/strip, race and off-road use. Comes complete with simplified ground strap, mounting screws, silicone coil gasket, low Ohm contact brush / spring and an ACCEL tan coil cover. Effective to over 9,000 RPMs.