Mortise Locks
A mortise lock is one that requires a pocket—the mortise—to be cut into the door or piece of furniture into which the lock is to be fitted. In most parts of the world, mortise locks are generally found on older buildings constructed before the advent of bored cylindrical locks, but they have recently become more common in commercial and upmarket residential construction in the United States.
The parts included in the typical mortise lock installation are the lock body (the part installed inside the 
mortise cut-out in the door); the lock trim (which may be selected from any number of designs of doorknobs, levers, handle sets and pulls); a strike plate, or a box keep, which lines the hole in the frame into which the bolt fits; and the keyed cylinder which operates the locking/unlocking function of the lock body.
The installation of a mortise lock cannot generally be undertaken by the average homeowner since it is labor intensive and requires a working knowledge of basic woodworking tools and methods. We at Marshall's are installation specialists, We use a mortising jig which makes precise cutting of the pocket a simple operation. Our experienced installers will also take care of whatever external trim you decide on. Since a mortise lock typically accepts a wide range of other manufacturers' cylinders and accessories, they allow for architectural conformity with any lock hardware already on site.
Some of the most common manufacturers of mortise locks in the United States are Arrow, Baldwin, Best, Corbin Russwin, Emtek, Falcon, Schlage, and Sargent.