The hub size is 73.1. The inner bore on the wheel is 66.1.

whats the difference then btw

66.1 spacers

and

66.1/73.0 spacers

Store - Taper Pro USA, Inc.

2 different models ?

Ok so those spacers (the 66.1/73.0) essentially have the hubcentric ring already built in. Notice the different color on the inside half of the spacer. The other spacer is simply a 66.1 bore all the way through. If you got those spacers (the 66.1) and have wheels with inner bore of 73.1, then you need the hubcentric rings to prevent vibrations in the wheel.