The rotor had opposing
poles same as any rotor, but with the one end open the poles were attached
in the middle with a plastic ring.
Kinda hard to describe!
Greg

you're almost right Greg, that "plastic ring" on the DELCO SI brushless ia
actually a mylar coated aluminum ring that wont disturb the field current in
the poles, but yet cuts dapers the harmonic vibration of the poles so they
don't stress crack , and fly apart. LOL!, I've seen that happen, though..it's
rare, but when it does happen...theres hardly a good bolt left in the unit.