To operate mortise locks with door hardware, they are supplied with different square holes in the lock follower.
- window: 7 mm
- apartment doors: 8 mm
- front doors: 10 mm
- fire doors: 9 mm
Door hardware, handle and rosette sets are also supplied with square pins of 8 - 10 mm, depending on the application.
Tubular frame locks are supplied with 8 or 10 mm square, depending on the application.
For the user it is usually not obvious which square size is used.
Therefore, in practice it happens that you have to combine these different square dimensions.
Reducing bushings are available for this task.
Reducing bushings are available in various materials and sizes.
- 10 to 9 mm
- 10 to 8 mm
- 9 to 8 mm
- 8 to 7 mm
The reducing sleeve is positioned centrally in the lock area. This allows the lever handle and knob to be mounted from both sides without the reducing sleeve interfering.