*T & Cs apply

Window Mechanism Measuring guide

Changing a window mechanism is quite easy. The hardest bit is Identifying the correct one

Just follow the guide below and you will soon know which mechanism to buy.


1)      Remove the window lock from your window.

2)     Hold the strip horizontally (Left to right) with the gearbox pointing downwards.




3)      Measure the total length of the lock. (Left to right)




4)       Turn the gearbox over so it's now facing upwards. Check if the gearbox is in the middle of the metal strip or to one side.  If it’s to one side, you need the offset version,  if it’s in the middle you need the inline version.



5)      Next you need to measure the size of the gearbox.  This is one of the most important measurements. So we will need to measure from the middle of the screw holes to the base of the lock.




So now you should have 3 sizes

1 Lock lenghth

2 The gear box orientation ( offset or inline)

3 The backset size.


Either give us a call on 01204 652211 to take your order and advise OR order online at