The From the Anvil 4\" Ring Door Knocker Black is ideal for use on painted or natural oak doors and is made from malleable iron. The ring width is 100mm, the ring length is 106mm, the fixing plate size is 47mm and the stud diameter is 49mm. Sold individually, it comes complete with fixings. Black Knocker The knocker has a black finish - this is baked in a high-temperature oven to give it good durability and can be used internally or externally. To remove dirt deposits, simply wipe over with a lightly oiled cloth from time-to-time and this will restore it to its original condition.