A French door[24] has two rows of upright rectangular glass panes (lights) extending its total size; and two of such doors on an exterior wall and and not using a mullion separating them, that open up outward with opposing hinges to some terrace or porch, are often called a French https://beckettgoua84184.national-wiki.com/661308/navigating_the_market_for_solar_cleaning_tools_opportunities_and_challenges