Benchtop Protector Pass-Through Laboratory Hoods can be operated from either side. Mounted in an island or peninsular configuration, the hoods offer unobstructed viewing from either side, and thus they can be used for conducting chemistry demonstrations or to observe students while using the hoods. An optional 15× 24 right–side mounted, clear tempered safety glass viewing window further enhances visibility. The hood can also be installed in a wall between two rooms to permit safe transfer of chemicals and experiments. An audible sash alarm sounds when both sashes are opened at the same time. Clear, vertical-rising tempered safety glass sashes provide maximum visibility.