The Ei166RC is an Optical Smoke Alarm that runs on 230V AC mains power, and has built in tamper-proof rechargeable Lithium cells that act as a battery back-up in the event of mains failure. These rechargeable Lithium cells are designed to have a ten-year life and outlast the life of the smoke alarm. They provide up to six months of smoke alarm operation without mains power. The Ei166RC also has Remote Control capability - allowing the detector to be controlled remotely from a Control Switch (Ei1529RC). This then allows remote Test, Locate and Hush functions to be performed. If the Ei166RC is also interconnected to other Ei RC mains powered alarms, then the whole system can be controlled remotely. Up to twelve alarms can be interconnected which will cause all alarms to sound when one unit senses smoke/heat. A Manual Call Point (MCP401RC) is also available. The Ei166RC is supplied with the Easi-fit base that allows very quick and simple installation of the smoke alarm, combined with simple detector head removal and replacement. The Easi-fit base automatically connects both mains power and battery as the detector head slides on. The Ei166RC has other advanced features such as integral insect screens, to reduce the chances of false alarms, and built in circuitry to aid suppression of voltage transients and RF interference to further reduce the chances of false alarms.