Abstract: A multi-glazed window unit of the type wherein parallel panes of a light transmitting material are sealed in a spaced apart relationship and the atmosphere between the sealed panels is treated to remove moisture therefrom. A housing containing a desiccant is positioned between the sealed panes along one outer edge of the unit. The housing is divided into two zones, the first zone being open to the atmosphere so that any moisture present in the atmosphere at the time the unit is sealed is immediately removed therefrom by the desiccant in this zone, and a second zone that is shielded from direct exposure to the atmosphere whereby the desiccant in this zone remains in a condition to remove moisture from the atmosphere which may penetrate the seal at a later time.