Example- If you set the scale at a measurement of 15 mm, you will get a ball size of diameter 30 mm. The attachment has both Imperial as well as Metric graduations on either size of the attachment. Pls note that we do not deliver to the PO Box Addresses. Please be aware that some countries may have local import regulations which restrict certain products from being imported. We take complete onus and responsibility of supplying you a completely brand new product without any manufacturing or transit damage.This item is in the category "Business & Industrial\CNC, Metalworking & Manufacturing\Metalworking Equipment\Metalworking Lathes". The seller is "assortstools" and is located in this country: IN. This item can be shipped worldwide.