Used where door is opened by pulling or pushing it only. In double doors, they are used with dummy pairs of levers or knobs. They also can be used in the top of a small closet where pull may be used. The ball is pushed by spring tension into notched brass plate in jamb above door. Locking mechanism for an entrance door or other door, in which a bolt moves with a turn of a key into a jamb.
Deadbolts can be a single cylinder or double cylinder.
With a single cylinder deadbolt, a key is used on one side, and is turned by hand on the other side. With a double cylinder deadbolt, a key is used on both sides. Double cylinders are only recommended where no one needs to go through a door in case of emergency. This strip of wood is where the door comes to rest when it is closed. It stops the door from moving any further, and also covers the gap that would otherwise appear between the door and the jambs.