Safety Technology International, Inc. STI-3300 Wireless Doorbell Extender with Receiver Connects to Existing Hardwired Doorbell, Part of Musical Wireless Chime Series Wires onto existing doorbell chime box inside the building or home Extends the range of which you can hear existing doorbell unit for example to a garage or basement. Up to 500' from the chime to receiver Receiver has low and high volume adjustment UL & CUL Listed, FCC & IC Compliant. Limited one year warranty.