Door Knocker. Knock, knock! Once a sign of their homeowner’s profession, doorknockers now come in a variety of designs & finishes for everyone’s style. Step-up your curb appeal & add value to your home with finishing touches like a knocker. Made of 100% black cast iron with our Exclusive rust-resistant RSF powder coat finish make this knocker a knock out! Easy installation, thread bolts through the door for secure mounting. Mounting hardware included. Measures: 5 1/2 in. H x 1 in. W.