I think my calipers are going to caliper hell. I Was on the phone with the company when I measured the dimensions three times on the old ring but the new ring does not fit in the groove. They are for the same piston but a different application. These rings look to be coated. So I was wondering IF some granite wet paper and light oil oculd come to my rescue or do I need to post for another ring. I may have to buy a set as the man that sold them to me broke up a set for me... Nice of him to do and I do not want to ask him to do that again. I know about lapping them to the bore but I do not know if people lap them thickness wise.