tapping card on mullion reader


If you’re shopping for an access control system, you’ll need to choose which type of reader you want. The type of reader you choose will change how people access and navigate your property. If you’re considering a fob or key card system, you might want to purchase a mullion reader.

In this post, we explain what a mullion reader is and how it works. Then, we go over the benefits of installing a mullion reader and outline the best way to use them on your property.

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What is a mullion reader?

A mullion reader is a special, miniaturized kind of access control reader that is thinner than a standard reader. Mullion readers are named after mullions, which is the term that door- and window-makers use to refer to a specific part of a doorframe.

As you might have guessed, mullion readers are designed to be installed on mullions. And consider any of the doorframes you’ve passed by today — they’re usually pretty thin. Because mullions are thin, mullion mount card readers are slim to match.

Even though a door mullion reader might be smaller than a standard reader, it has all of the same capabilities. You can set up a mullion reader to accept any sort of wireless credential. You can choose between prox card readers that use Bluetooth or RFID, or even smartphone-based readers that residents can unlock with an app.

Mullion keypad readers that use PIN codes are also common. And, you can install multiple readers across your property to manage access to different areas.

Use a mullion reader to manage access to places like:

  • Gyms
  • Co-working spaces
  • Laundry rooms
  • Supply closets
  • Server rooms


Watch how the ButterflyMX keypad works:


How a mullion reader works

While mullion readers are smaller and more compact, they function exactly the same as a standard reader. Mullion readers depend on wireless transmissions to receive a resident’s credentials.

Under the hood, a reader might be powered by a few different technologies. You can choose between different technologies, like RFID waves, NFC waves, or Bluetooth. Many modern readers use more than one technology and can scan a greater range of credentials.

A mullion reader access control system consists of:

  • Mullion reader. The reader’s job is to “read” a credential and send it to the control panel for verification.
  • Credential. Different readers accept different credentials. For example, residents use PIN numbers to unlock mullion keypads, while proxy card readers require residents to scan physical cards.
  • Control panel. The control panel is the “brains” of an access control system. While mullion readers receive the credential, the control panel actually verifies that credential and sends a signal to the door to unlock. Staff also use the control panel to edit access permissions and add or remove residents from your system’s directory.


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Mullion reader benefits

Mullion reader systems are popular and convenient access control solutions used at multifamily and commercial properties.

The benefits of using a mullion reader include:

  1. Can be installed in more places
  2. Accept multiple types of credentials
  3. Easy to use


1. Can be installed in more places

Don’t be fooled by the name — mullion-mounted card readers were designed for use on doorframes, but you can install them anywhere you like. And because mullion card readers are small, you can install them in more places than you could a standard reader.

Pro tip: If you’re installing a card reader outside, make sure it can stand up to the elements. Look for a reader that’s rated for the outdoors.


2. Accept multiple types of credentials

Compared to other access control hardware like keypads, a reader can have more than one sensor and more than one way for a resident to gain access.

For example, a reader may have both a keypad and wireless sensors, which gives residents the flexibility to choose how they gain entry.

However, convenience may only be a priority for some of the rooms and spaces throughout your property. And a mullion reader isn’t the only security solution your property should have. Well-rounded properties also feature hardware like intercoms and vehicle readers, depending on the security needs of a specific area.


mullion reader with multiple credentials


3. Easy to use

Many mullion readers work with cards or fobs. What could be easier than taking out a fob and simply holding it up to a reader?

And these days, most of your residents have smartphones in their pockets, anyways. So, choose a reader that residents can unlock with their smartphones for maximum convenience.


The best way to use mullion readers

Mullion card readers are great for entryways where there’s only a limited amount of space to mount an access reader. But while mullion readers are small and compact, they can’t be the sole solution your property uses to maintain security.

For example, what if you want to allow your residents to open doors remotely? Because readers need a resident to be in close proximity, they have no way to enable remote unlocking. And for other areas of your property, like parking garages and gates, vehicle windshield tags are more efficient because they spare residents from needing to get out of their cars or roll down their windows to scan a credential.

The best way to use mullion readers is alongside other access control devices, like keypads, vehicle readers, elevator controls, and intercoms — and that’s where ButterflyMX comes in.


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ButterflyMX unified property access control

ButterflyMX is your one-stop shop for all of your access control needs. Electronic access control simplifies access for guests and visitors alike, but only if used correctly.

Keeping track of one database for your fob system and another database for your intercom is a recipe for disaster. And residents will feel frustrated if their credentials work at some doors and not others.

ButterflyMX’s access control products seamlessly integrate with one another and make property-wide access simpler for staff, guests, and visitors. With one click, staff can make changes, add and remove tenants, and edit permissions — and those changes will be shared across every single access control device on your property, whether it’s a keypad outside an amenity space or a video intercom at your front gate.



  • A mullion reader is a smaller type of reader that’s designed for use on doorframes. However, you can install them wherever you’d like.
  • Mullion readers can take multiple types of credentials, from RFID waves to Bluetooth to NFC. Residents can unlock a reader with key cards, fobs, or their smartphones.
  • The best way to use a mullion reader is as part of a larger access control system alongside other hardware, like intercoms, keypads, and vehicle tag readers.


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Ferdison Cayetano

I’m a proptech enthusiast from New Jersey who’s looking forward to the innovations that will revolutionize real estate.

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