Security locks

High end sliding patio doors feature a multi-point lock design – at least with 2-locking points. Some patio doors offer additional 2 locking points in the jamb side of the door making the total number of locking points 4, hence the name of the mechanism – four-point locking system.
Additionally, you may want to consider a night-vent foot-lock. This push button spring-loaded foot bolt is easy to lock and can be set to allow ventilation while having extra security.