Cragar Mach 8 Spacers

Dude, those look sketchy to start! Looks like they were cast in someone's sand box. How do they work, is the OD of the casting the ID of the lug hole or are they just spacers held in a circle? back look like these? just a normal spacer but it looks like they are unilug so the crescent spacer may locate the lugs...?

PB220008.jpg