What is offset? Offset is the center-to-center measurement between Dead bolt Bore and Latch Bore. Offset may vary from door to door, and on custom doors could be drilled out to any specification. However it is recommended that you use 6 inch or 9 inch offsets, but it is up to the description of the installer if the door is not pre-drilled.
ONE PIECE ENTRY SET
One piece entry sets usually have standard 5-1/2 inch or 6 inch offset, sometimes manufacturer might offer other offset choices and also make custom offset entry sets. Graphic bellow is an example of a one piece entry set with standard offset.
TWO PIECE ENTRY SET
Two piece entry set is where Dead bolt is a separate part of the entry set and not mounted on the same plate. Bellow is a graphic with a popular 6 inch offset.
Bellow is a graphic with a popular 9 inch offset.
DUMMY SETS require no door prep. Dummy handles are surface mounted and may be located anywhere on the door you choose, but they are usually located to match the appearance of nearby operating locks.