This is the "undercover" magneto....last time I tried to get one, Allan said that he wan't sure he'd make any more. It uses a coil, mounted remotely and connected by wires. It generates it's own spark, so doesn't need the alternator, but if you want lights, horn, etc, then leave the existing alternator in place, or fit a higher output one for better lights.
The early ones used modified Fairbanks-Morse mags with a distributor cap....so maintained the single fire system, and mounted in the front of the engine, run by a toothed belt. The coil, points, and everything were all inclosed in the housing, so the only wires were the plug leads and a kill switch wire mounted to a stud.
These undercover mags are dual fire, use a HD style coil. They are essentially a timed, high voltage alternator linked by wires to a remote mounted coil.