Ring has 4 sizes (inner diameter) can be selected: 1.42'' (36 mm), 1.57'' (40 mm), 1.77'' (45 mm), 1.97'' (50 mm).
Because ring is not a standard circle, so these inner diameters are figured out by formula.
Please watch its details in the picture.
This ring is only compatible with the cage whose ring is the same as it. If you are not sure, please contact us before purchase.
These sizes may have a little error because it's made by hand.