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. The Extension Sleeve is required when fitting heater or deep bases; the Adaptor Ring is needed for fitting sounder bases, beacon bases or sound beacon bases. Further details are given in the table below. The Extension Sleeve and the Adaptor Ring are sold as an Accessory Kit, part no 45681-218. The Deckhead Mounting Box has 6 cable access ports for M20 glands and is secured to the mounting surface via two 5.4mm holes in the webs.