These springs are used on a wide variety of garage doors, from standard singles to caravan doubles. The most important aspect of fitting the correct springs to a door is to ensure the installer is aware of the correct weight of the door, as well as the correct width and height.
The springs are manufactured and tested to withstand at least 15,000 operations.
Over time the spring needs adjusting and the spring will start showing fatigue to the point where it will break. This is normal for a spring to end its lifespan but with correct maintenance you can prolong the life of a garage door spring significantly.