The B200S-LF-WH and B200S-LF-IV sounder bases are used with addressable detector heads. Refer to the appropriate manual for more information on sensors. The B200S-LF-WH/B200S-LF-IV low frequency sounder base generates a low frequency tone around 520 Hz. Studies have shown that low frequency audible devices that operate around 520 Hz are more effective in waking individuals in sleeping areas.The sounder base is capable of producing a variety of tone patterns, including the distinctive three-pulse temporal pattern (ANSI Temporal 3) fire alarm signal now required by NFPA 72 for commercial and residential applications. The B200S-LF-WH/B200S-LF-IV offers maximum flexibility in configuration and operation to meet or exceed the requirements of UL268 and UL464 for Continuous, Temporal 3 and March time patterns. The temporal 4 pattern meets all requirements of UL268 and UL2075, as well as, private mode setting of UL 464.