How to determine the length of a Mortise Cylinder

One of the most popular questions we get asked at CLK Supplies, LLC is how to correctly determine the length of a Mortise Cylinder that I need. In most cases, you’ll have a Mortise Cylinder that you’ll be replacing so that it is easier for you to tell the length of the one you have and the tailpiece you need.

Mortise Cylinders come in three different sizes:

  • 1"
  • 1 1/8"
  • 1 1/4".

The part numbers are:

  • M-100 for a 1”
  • M-118 for a 1 ⅛”
  • M-114 for a 1 ¼”
The standard applications for these would be:


  • 1” Mortise Cylinder for aluminum storefront doors, also known as Adams Right storefront doors.
  • 1 ⅛” Mortise Cylinder for aluminum storefront doors and exit devices.
  • 1 ¼” Mortise Cylinder for exit devices or Mortis case locks.

How To Measure Mortise Cylinders

Grab for instance an M-100 from a 1” Mortise Cylinder and measure it from the front of the face plate to the back of the brass body, not the tailpiece. You’ll see that it is 1” long.

n regards the tailpiece, the 1 1/4” Mortise Cylinders come with the Yale standard cam; the M-118 comes with two tail pieces: the Yale standard cam and a little Adam’s right and the M-100 comes with the Adam’s right cam.


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