Euro cylinders are used in the vast majority of double glazed doors, french doors and patio doors they are used to secure the door's multi point locking system.
Cylinder door locks are not difficult to replace if you have basic DIY skills, you only need two measurements.
Your cylinder locks should be as flush as possible with the handles, maximum projection is 5mm - if you current lock sticks out by more than 5mm either side of the hanldes then choose a smaller size....
Read More...