French door screens come in both sliding and hinged design. They are both what describe as centre opening doors. In the case of hinged doors there will be one active door which will contain the lock and one non-active door which will be in most part fully closed, however openable when needed. The non-active door will contain flush bolts that are activated by one single lever that will send vertical rods out of the bottom and the top of the door that fully lock it into the door jamb. Three point locking is available and a very wise option to secure the door more fully.
In the case of sliding doors than the same will apply, that is there will be an active door which contains the lock and a non-active door that will have a H receiver that accommodates the active door once they are close together locking the door in the centre. Sliding doors usually come with an interlocking system.
At Seconline we provide all of our sliding security doors a frame interlock which is designed to fit to the back of the doors locking in to the receiving interlock which is located usually on the back of the fixed glass panel. This has the effect of locating the doors precisely in the centre position at exactly the same time as they engage together effectively locking them both in the centre and on either end. If interlocks are not available on the fixed glass panel then they can be provided and installed. It is absolutely essential to have these receiving interlocks, otherwise they will not be classified as a security door and will be possibly unsafe.