the obstruction light is a recognizable signal light used to indicate a building's stairs and the height of that building. - 航空與環境高峰會議 個照片及圖片檔電燈泡
the obstruction light is a recognizable signal light used to indicate a building's stairs and the height of that building. - 航空與環境高峰會議 個照片及圖片檔電燈泡, 危險, 安全