A 58 to 90 inch guard is being used to cover two double hung windows.
If you don't have enough room inside the window frame, you can also screw the side post into the molding that surrounds the window frame.
The window opening should not exceed the height of the window guard (21 3/8 inches). If it does, you can use a window stop to keep the window from opening beyond the guard.
The Guardian Angel comes with 4 emergency release buttons, 2 on each side.