There is one important thing you need to know if you are replacing an existing Night Latch, this is what is called the Back Set Measurement, the two most common sizes are 40mm and 60mm, there are however a few older traditional types that are different to this, I have come across 50mm and 55mm on the odd occasion but they are the exception to the rule.
The reason this is so important is because they are not interchangeable, if you have a 40mm Back Set you cannot remove that and fit a 60mm version, this is due to the hole that is drilled through the door being in the wrong place, the Back Set relates to the measurement from the edge of the door to the point where you drill a 32mm hole through the door to accept the Rim Cylinder.
So if you are replacing an existing Night Latch please make sure you have checked this prior to ordering, if you have any questions relating to this please don’t hesitate to contact us on 0800 0612 688