Some types of interior window grids include grids with a spacer, grids without a spacer and grids inside the glass. Window grids can be permanent or removable.
Grids inside the glass create the look of separate panes from the middle of the glass. Grids with a spacer are grids on the interior and exterior of the window with a spacer inside the glass. Grids without a spacer do not have a spacer inside the glass, but they are also grids on the interior and exterior of the window.
Removable grids have the benefit of being easy to clean. They are an ideal choice for the exterior of the window.