In the apartment that I am renting, the bedroom door knob does not have a lock on it. I am looking to replace the door knob with one that has one. However, the door seems to have a knob mounting that I am unfamiliar with. The locks that I've changed in the past have the screws inside the lock, and it seems that this one has them outside of the main hole. It also seems like a larger handle. Is this a larger lock then normal? What is a cheaper type replacement with a lock on it?