This sliding garden patio door has an old style push lock as part of its locking mechanism. The lock works by inserting a key, turning it and then pulling out the lock cylinder. The lock on this particular door was not working any more and had jammed so needed replacing. We did an exhaustive search for a matching replacement but found that the lock had been discontinued for several years now. Our only option was to drill out the existing cylinder and replace it with another type of stationary push lock which fitted existing hole. This lock cylinder could not be pulled out of the door as with the previous one but did the job of locking the door just as well.