The EIB171RFAU consists of a strobe unit, and runs on 230V AC Mains power with a built in long-life sealed lead-acid rechargeable battery. It is designed for daytime rooms as a visual indicator. If a bedroom is to be covered then the use of an EIB170RFAU alarm should be used which includes a vibrating pillow pad. To be ordered with: EIB3016 - Mains powered photoelectric smoke alarm or EIB650iRF - Photoelectric battery smoke alarm.