Screwbolt----thanks for the drafting idea. I understand the difference between mm and cm etc etc. However I think it is poor customer service to give a customer the dimentions they seek in a format that is not widely used. All i wanted to know (from Talley) was how much higher the "HIGH" mount was compared to the "MEDIUM" one I currently have. Why they responded with "1/10"" I do not know. All I have are standard/english (whatever you want to call them) tape measures which have sixteenths (1/16). Why Talley couldn't say that the HIGH mount was almost 1/8" taller I do not know. ---DrAsus