About this item Safety Technology International, Inc. STI-3350 Wireless Doorbell Chime with Receiver for STI 2015 Musical Chime Series. Tired of the old ding-dong doorbell sound, well then change it up. This musical wireless doorbell chime is the answer you have been looking for. Installation is fast and easy, mount the button to the exterior of the door and plug the receiver unit into any indoor electrical outlet and you are ready to go. There are ten sounds that can be selected with the push of a button on each transmitter. Unit is UL/cUL Listed, FCC certified. Unit operates up to 500 feet. Supervised low battery voice alert. Volume adjustment: low, medium, high. Includes CR2032 battery. Selectable sound options are: Ding, Dong, Ding-Dong, Westminster – 4 note, Westminster – 8 note, Knock Knock, Jingle Bells, Barking Dogs, Bicycle Bell, Buzzer. If you are looking for an aditional doorbell only for this product check out model # STI-3301. Safety Technology International, Inc. “We protect the things that protect you.