Hardy hole is 7/8" and the round is just over 1/2" sizes are metric but I don't have a metric ruler. The item "Antique Mousehole or #95 Anvil with Mouse Hole Stamp" is in sale since Friday, January 15, 2021. This item is in the category "Collectibles\Tools, Hardware & Locks\Tools\Blacksmithing".
The seller is "1stanleytool" and is located in El Dorado, California. This item can be shipped to United States.