In a window, a pane is a part of glass. Windows are available with single, dual and triple panes. Multiple panes, which are full of gas, raise the window insulation abilities.
A pane may be a single square of glass, as is most frequently true for contemporary windows, the whole sheet within a sash.
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Steel Window Bronze
This really is a window.
Custom Spaces Design
The bottom here features a pane without a muntins.