BEST SELLER! Great for large homes and businesses that need to transmit over long distances, the LRA-D1000 has the power you need to penetrate walls that typical products cannot. A selector switch on the side of the door chime can be set to "flash," "chime," or "flash and chime." A great choice for use in residential applications for the hard of hearing or in noisy, commercial environments. This is a great product for homes of all sizes and mid-sized businesses. For large commercial spaces or if you need a business door chime system with external accessories such as Fire Alarm Bells, Loud Sirens, or Strobe Lights, visit the ERA-UTDCR Business Doorbell.