This eye catching polished brass porthole mirror opens just like an actual porthole. It measures 20"Dia. (13.5" for the mirror itself). We are a retailer and do not advise on the installation. The manufacturer does not supply any parts with this item. The only item being sold is the porthole mirror itself as pictured. It will add a definite nautical touch to wherever it's placed and is a must have for those who appreciate high quality nautical decor. It makes a great gift, impressive decoration & works well in many decor environments.