all of us want to be safe & secure in our own homes. But the problem is we adorn our doors with new fancy smancy locks and signs from the alarm company be-questing crooks and thugs to stay away. bottom line (techno-mall.com) one single lock fits all types of doors/window. how ever this lock is invisible from the exterior. Crooks do no know how to break it or damage it or pick or bump it.http://techno-mall.com/ the lock is simple to use and install.