A door-knob rosette is an escutcheon that is used when a full back plate is not needed. It is often used on the backside of the door that uses a rim-lock (box surface lock). Underneath the door knob and rosette, a keyhole escutcheon is used. Most rim locks were used pre-1900. This Victorian rosette is of that era. If a keyhole cover is needed, you will search for a cast iron one that will complement the rosette. The cast iron rosettes look especially nice behind a black porcelain knob. This Victorian designed rosette measures 2 1/8 inches round. On the backside of the rosette, are three prongs for gripping into the wood. The opening for the door knob neck is approximately 5/8 inch. Cast-iron straight-necked porcelain knobs work well. Many straight-necked stamped metal knobs work, but most crystal knobs have a neck too thick for this rosette. Screws will be provided.