I don't know why he's so perplexed at the points inside the ring -- all of the Bosch pre-war magneto/generators work that way. I have three of them, and the design is very clever. The same unit can be made to spin in either direction (gear or chain drive) and can fire 1, 2, or 4 cylinder engines of varying configurations with suprisingly few part changes. They only require a bit of notor oil every 1200 miles and new brushes about every 10,000 miles.