I am trying to replace the lock mechanism on the door to my shed. The location is the Netherlands so my apologies if any of the terms I use do not make sense.

I bought a 30/10 cylinder lock (so that it can only be opened on one side) like this: 30/10 cylinder lock

Now I am trying to find a mortice lock that can be used with this cylinder lock because the current mechanism doesn't work with cylinder locks. So something like this:

mortice lock

However, I am confused about the sizes. All the videos I watched use 30/30 cylinder locks and my logic is telling me that if I place a 30/10 cylinder inside of that lock it will be lost forever inside!

Am I missing something here? Will my 30/10 cylinder lock fit in every cylinder mortice lock? Or do I need to look for something specific?

1 Answer 1


The 30/10 refers to the length between the black tab and the end of the cylinder. Which means that a 30/10 is a 30/30 with the back hacked off but compatible in every other way.

The way a eurocylinder lock secures itself is in 2 ways:

First the little black tab hooks into the track of the mortise, you need the key to align the tab with the rest of the cylinder body to insert or extract the cylinder.

Second there is a screw that will go from the plate all the way through to the threaded hole under the black tab.

This means that while installing you need to ensure that the tab engages with the locking mechanism in the mortise and then the screw will line up.

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