Door And Lock Terminology 101: Strikes, Hinges, Astragals, & Mullions

Door and locking hardware isn’t generally a subject of interest for people outside the industry. More often than not, we simply ask for pictures when our customers don’t know how to describe their issue correctly. Education, as a store manager, design consultant, construction department or anyone else involved with the door and hardware of commercial buildings, can speed up the process of both service requests and ordering. We hope to shed light on the complexities of your facility’s doors, hardware, and locks over the next two weeks in a four-part series on door and lock terminology.  This first post of the series will cover strikes, hinges, astragals, and mullions.


  • A strike is a metal fastening on the door frame into which the bolt of a lock engages to secure the door.
  • Sizes: There are two commercial sized strikes:
    • ANSI Strike – These strikes meet current commercial building codes.  They are much longer than residential strikes.
    • T-Strike – These strikes are much smaller and less common than ANSI strikes.

door and lock terminologydoor and lock terminology, t strike








  • A hinge is a jointed device that attaches the door to the frame.
  • There are three main types of hinges:
    • Continuous Hinge – A continuous hinge runs the entire length of the door.  It is most commonly used on heavy doors made of aluminum and glass or steel.
    • Butt Hinge – These are the more traditional hinges that you see on residential doors and/or interior doors.  They come in varying heights.  Security features are available in butt hinges to stop people from being able to remove the door from the outside.
      • Non-Removeable Pin (NRP) – NRP butt hinges are made such that the pin attaching the two hinge leafs cannot be removed.  Without this feature the door can be removed from the opening of the door by removing the pins while the doors is closed.
      • Security Studs – Security studs lock one hinge leaf into the other when the door is closed.  If the hinge pins are removed, the security studs make it so that the door cannot be removed.
    • Pivot Hinge: Pivot hinges are mounted into the floor and the top of the door frame, and the door pivots on them.  These are most often used in glass/aluminum and herculite full glass doors.

door and lock terminologybutt hinge_mckinney


pivot hinge with label_free use










  • Astragals act as a seal between two doors or between the door and the frame that provides protection for the locking device.  They stick out past the outside edge of the door and cover the gap between the doors or the door and frame, depending on its application.

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  • A mullion is a vertical beam that forms a division between two doors in a single opening.  They provide structural support, allow for a strike application in place of vertical rods, and allow the doors to swing different ways.  Mullions can be permanent fixtures or removable.

Googledoor mullion

About Katie Willie

Katie Willie is the Marketing Director at LockNet. After growing up around LockNet, Katie formally joined the team in 2007. She manages the LockNet brand by developing and strengthening the marketing program. Establishing LockNet as a go-to-resource, she manages LockNet’s content creation efforts. Outside of work, Katie enjoys chasing her toddler and playing with her dogs Cody and Ollie (LockNet’s original Chief Morale Officers).

3 Responses to “Door And Lock Terminology 101: Strikes, Hinges, Astragals, & Mullions”

  1. Exit Door - Installing an Exit Door with Panic Hardware

    […] always recommend a continuous hinge for commercial facilities, especially on exit doors. They increase security and decrease the […]

  2. shawn miller

    Can you tell me if there are problems with doors that have astragals. I am thinking about installing a pair of doors that have an astragal and wondering if they operate well. I am also wondering about the safety issue with an astragal door. It seems like it would be easy to bust open a door since it meets in the middle. Thanks.


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