Our Language

We've been in this industry for a long time, so we created a list of terminology to help you distinguish all the different parts. 

Active Door

The leaf that opens first, and the one to which the lock is applied. 

Back Check

An optional feature in hydraulic door closers slowing the opening swing of a door somewhere between 60° and 85° of opening. Designed to protect an object behind the door. Not intended to act as an overhead stop.

Ball Bearing Hinge (Butt)

A hinge equipped with ball bearings between the hinge knuckles to reduce friction.

Bevel of Door

The angle of the lock edge in relation to the face of the lock stile. Standard bevel is 1/8" in 2" (3.2mm in 50.8mm). If otherwise detailed it must be so noted in ordering locks.

Bored Lock

Lock or latch whose parts are intended for installation in holes bored in a door. 

Change Key 

The different bittings or tumbler arrangements in a series of locks.

Checking Floor Hinge

A device placed on the floor that combines top and bottom pivots for hanging the door with a controlled-speed closing mechanism.  

Cylinder of a Lock

A term used to describe bored locks, which have a cylindrical case into which a separate latch bolt case fits. 


A lock both having no spring action or bevel, and which is operated by a key or a turn piece.

Door Closer Check

A device combining a spring for closing and a compression chamber into which the liquid or air escapes thus permitting free operation of the door slowly, thus providing a means of controlling the speed of the closing action.

Dummy Cylinder

A mock cylinder without any operating mechanism for use where the effect is desired. 

Dust proof strike

A strike with a spring plunger that completely fills the bolt hole when the bolt is not projected.

Electric Strike

An electrical device that permits releasing of the door from a remote control.

Exit Device

A door-locking device designed to grant instant exit by pressing on a crossbar that releases the locking bolt or latch. 

Floor Closer

A closing device installed on the floor under
a door.

Foot Bolt

A type of bolt applied at the bottom of a door and arranged for foot operation. Generally, the bolt head is held up by a spring when the door
is unbolted. 

Guard Bar

A series of two or more crossbars generally fastened to a common backplate to insure protection of glass or screen in a door.


A fastening device consisting of a loop and a slotted hinge plate, normally secured with
a padlock.

Hinge Stile

The stile to which the hinges are applied as distinguished from the lock stile.

Indicator Button

A device used in connection with a hotel lock to indicate whether or not the room is occupied.


The aperture in lock cylinders that receives the key and closely engages with it throughout its length.


A projecting handle for operating a lock.

Latch Bolt

A beveled spring bolt, usually operated by a knob, handle or turn.

Lip of Strike

The projecting part on which the latch bolt rides.

Mop Plate

A narrow plate similar to a kickplate, of sufficient height to protect against the swish of the mop.

Mortise Bolt

A door bolt designed to be mortised into a door rather than applied to its surface.


An auxiliary lock having a spring latch bolt and functioning independently of, and providing additional security to, the regular lock of
the door.

Panic Exit Device

Type of door opening mechanism which allows users to open a door by pushing a bar.


The round part containing the keyway and rotated by the key to transmit motion to
the bolt(s).

Push Plate

A plate applied to the lock stile to protect the door against soiling and wear. 


A term used to describe the abutting edges of a pair of doors or windows so shaped as to provide a tight fit. One-half of the edge projects beyond the other half, usually 1/2″. Also used to define that portion of a door frame into which the door fits.

Reverse Bevel

A term used to indicate the direction in which the latch bolt is inclined: regular bevel for doors opening in, reverse bevel for doors opening out.

Roller Latch

A friction door latch employing a roller latch head under spring tension, which engages a strike having a recess formed to receive
the roller.


The bar or tube connected with the knob or lever handle that passes through the hub of the lock or otherwise engages the mechanism to transmit the knob action to the bolt(s).


A molding or strip whose purpose is to cover or close the gap between the edges of a pair of doors. Some types overlap, others meet at the centerline of the gap.

Backset (of a Hinge)

The distance from the edge of the door to the hinge.


A type of hinge designed for mortising into the edge of the door, and into the rabbet of a door frame. 


The projecting blade, cut in a manner that actuates the tumblers and permits the lock bolts to be operated. 


A rotating piece attached to the end of the cylinder plug to engage the locking mechanism.

Continuous Hinge
(Also called Piano Hinge)

A hinge designed to be the same length as the moving part to which it is applied as, for example, the lid covering the keyboard of

a piano. 


A device used on a pair of doors to ensure that the inactive leaf is permitted to close before the active leaf. Necessary when an overlapping astragal is present and exit devices, automatic or self-latching bolts are used with closers on both door leaves.  

Cylinder Collar

A plate or ring used under the head of a cylinder.

Dogging Device

As used in exit devices, a mechanism that fastens the crossbar in the fully depressed position, and also retains the latch bolt or bolts in a retracted position, thus permitting free operation of the door from either side. 

Door Stop

A device to stop the swing or movement of a door at a certain point. Also, an architectural term defining that part of a door frame against which the door closes.

Dummy Trim

Trim only, without lock; usually used on the inactive door in a pair of doors. 

Elbow Catch

A spring-loaded device embodying a rocker arm, and angle strike, for locking the inactive leaf of a pair of cabinet locks. 


A plate long enough to span a lock case and having holes for knob bushing, bit key, cylinder, turn the knob and similar operating members as required.

Extension flush bolt

A flush bolt in which the connection between the bolt head and operating mechanism is by means of a rod inserted through a hole bored in the thickness of the door. 

Flush Bolt

A door bolt so designed that when applied it is flush with the face or edge of the door.

Grand Master Key

A key that operates locks in several groups, each of which has it’s own master key.

Hand LH RH

A term used to indicate the direction of swing or movement, and/or locking security side of
a door.


Two plates joined together by a pin and attached to a door and its frame whereby a door is supported and is enabled to swing or move.

Inactive Door

Hat leaf of a pair of doors that do not contain a lock, but is bolted when closed, and to which the strike is fastened to receive the latch or bolt of the active door.

Key Change

The combination of cuts in a key that enables it to operate the lock for which intended.

Kick Plate

A protective plate applied on the lower rail of the door to prevent the door from being marred.


The enlarged part of a hinge into which the pin is inserted.


One of the two doors forming a pair of doors.

Master Key

Operates any quantity of cylinders of different individual key changes


A cavity made to receive a lock or other hardware; also the act of making such a cavity.


A fixed or movable post dividing an opening vertically.

Overhead Concealed Closer

A closer concealed in the head frame with an arm connecting with the door at the top rail.

Pin Tumblers

Small sliding pins in a lock cylinder, working against coil springs and preventing the cylinder plug from rotating until the pins are raised to the proper alignment by bitting of key.

Prison Lock

A heavy lock designed especially for use on
jail cells

Dutch Door

 a door divided into two parts horizontally(upper and the lower leaf), allowing one half to be shut and the other left open.


A horizontal member that joins the stiles. May be exposed as in a paneled door, or concealed as in a flush door.


A term indicating articles of hardware designed for application to the surface of doors and windows.


A trim plate attached to the door under the knob. It sometimes acts as a knob bearing.

Split Astragal

An astragal that is split through the middle, allowing each door leaf to
operate independently.

Spring Hinge

A hinge containing one or more springs to move the door into the desired position. It may be either single or double-acting.


A vertical member of the door structure; each door has two, a lock stile and a hinge stile.

Strap hinge

A surface hinge of which one or both leaves are of considerable length.


A metal plate or box that is pierced or recessed to receive the bolt or latch when projected. Sometimes called the Keeper.

Swivel Spindle

A spindle having a joint midway in its length to permit the knob at one end to be made rigid by the stop works while the other end is free
to operate.

Three Point Lock

A device sometimes required on three-hour fire doors to lock the active leaf of a pair of doors at three points.

Surface hinge

A surface mounted hinge is a type of hinge that is attached without a mortise being cut into the door or frame.

Template Hardware

A term indicating any item of hardware that is made to a template; that is, exactly matching the master template drawing as to spacing of all holes and dimensions.


A strip fastened to the floor beneath a door, usually required to cover the joint where two types of floor material meet.


Measurement of the maximum projection when the bolt is fully extended.

Thumb Piece

The small pivoted part above the grip of a handle to be pressed by the thumb to operate a latch bolt.

Transom Bar

That part of a door frame that separates the top of a door or a window from the bottom of
the transom.


A guard or obstruction that prevents operation of a bolt except by insertion of the proper key

Door Handing RH LH (Right hand, Left hand) 

Right hand reverse Left-hand reverse

If the door is swinging away from you the hinge is on the right side. for a left hinge door, if the door is swinging away from you the hinges are on the left side. Inswing or outswing only matters with exterior doors where they have a sill. The handing or hinging is still determined the same way.


Door handing is easily determined while standing on the SECURE SIDE (key side) or OUTSIDE of the door. LEFT-HAND REVERSE DOOR: The hinges are on the left and the door opens toward the outside of the room. LEFT-HAND DOOR: The hinges are on the left and the door opens into the room.