KUPO Elemack/Euro Starter KS-660M (M12) This is a cup part for the KUPO Elemack/Euro. The center screw hole is M12, and the two screw holes next to it are 3/8 inch. Please refer to the last photo for approximate size in millimeters. It has been used to some extent. Here is the product page: https://www.kuposhop.com/en/product-673578/KUPO-Elemack-Euro-Starter-M12-KS-660M.html