Abstract: This energy saving and burglar proof lock enables windows to be adjustably opened to about six inches, at night, for allowing fresh air to circulate throughout a dwelling, thus allowing the air conditioner to be turned off, and it further serves to prevent anyone from entering the windows. It includes a pair of plates, one of which is secured to the window frame, and the other is secured to the bottom window. It further includes an indented or toothed rod, welded to one of the plates, and slidably received in the other, the rod being held secured by a spring-urged pin.