OK, 180, you might have to help me out with the conversion. ID is 11/4"/ OD is 1 9/16th". I believe that to be ID 3.2 cm/ OD 4 cm. I don't own a micrometer, but it takes 5 shims to make 1 cm. The shims aren't all the same thickness as I had thought. I can ship you out one of the thicker ones if you like?