The Deckhead Mounting Box is a device which protects detector bases, sounder bases and sounder beacon bases from the ingress of water or other liquids. It is screwed to the soffit and accepts a variety of Apollo bases. The Deckhead Mounting Box is used on its own in most cases but there are applications where either an extension sleeve or an adaptor ring is required. An extension sleeve is required when fitting heater or deep bases; an adapter ring is needed for fitting sounder bases, beacon bases or sounder beacon bases. The extension sleeve and adapter ring are sold as an accessory kit. The Deckhead Mounting Box has six cable access ports for M20 glands and is secured to the mounting surface via two 5.4 mm holes in the webs.