A mortise lock is a more secure option for a residential or commercial door

A door lock body is the internal component that enables a lock to hold the latch or bolt in place. It can be used to secure a door from being kicked open or to provide added security against attempted break ins. It consists of the interior latch, handle or knob, and the strike plate which connects the frame to the lock. The strike plate is made from heavy duty metal and may be able to resist kicks, punches or other attempts at force.

The internal latch is usually made of a spring-type bolt held in place by a spring clip which when compressed allows the bolt to retract into the lock body and snap into place, locking the door. The handle or knob is what you actually use to operate the lock and pull or slide back the latch bolt. It is important to know how the latch bolt is oriented in the lock body before you choose the correct handle or knob. This is because some doors are "handed" (right or left hand swing) and require a specific latch bolt orientation.

Most locks are keyed and come with a set of keys to allow a person to unlock or close the door by twisting the handle on either side of the lock. Some locks, however, can be opened and closed without a key, such as with a cylindrical tumbler lock or an electronic lock. Cylinder locks are designed to be operated by the thumb or finger, and are ideal for homes with children or pets.

A mortise lock is a more secure option for a residential or commercial door. They are typically designed for keyed functions and require a pocket or "mortise" to be cut into the door frame for the lock body. Mortise lock bodies are available in different case depths, and the size of the pocket or cavity in the door will determine what type of trim (roses or escutcheon plates) is needed.

To find the right mortise lock body for your door, start by measuring the height of the door frame stile from the edge to the top. Then divide this number in half to find the "backset" value. This value is the distance between the center of the lock face and the center of the keyhole. This information is critical when choosing a mortise lock, as it will ensure that the new lock is aligned with the hole in the doorframe without having to drill additional holes.

To mark the location of a new mortise lock in the doorframe, measure from the edge of the doorjamb to the latch's midpoint and make a mark with a square. Then, using the centerline of the doorframe as a reference, mark where to drill the hole for the new mortise lock. Make sure to take into account the thickness of any recessed panels or glass in the doorframe. When drilling, be sure not to cut past the edges of the doorjamb or it could be possible for an intruder to kick the strike plate out of the way and gain entry through an unlocked door.