No supports or rafts needed.. Print slow

Inner diameter is approximately .74 in. (2.32 in. circumference) or 18.8 mm (59 mm circumference)... I believe that is around a size 9.

Ring sizing here
https://www.justmensrings.com/mens-ring-size-chart

Diameter to circumference calculator here
https://www.omnicalculator.com/math/circumference