Prima Polished Brass Diplomat Knocker PB709 Overall Size  (143mm x 140mm) Bolt centres 4 1/2″ (112mm) This Polished Brass Diplomat Knocker is a beautiful solid brass piece and during the manufacturing process this item is highly polished and is finished by a final coat of laquer ensuring a highly polished finish which needs no maintaining. Care – Simply wipe with a cloth .