Mini Yet Mighty After carefully researching, we have re-this receiver, giving it a mini size of just 2.8 X 3.1 Inches, so that it won't block off any neighboring power sockets. The performance, however, has not been compromised. A huge selection of 52 melodies allows you to easily choose one that suits you. The Next and Previous buttons allow you to go back and forth when choosing a tune, meaning you do not have to cycle through the full list again if you accidentally skipped the one you wanted. Durable and Waterproof Transmitter The built-in 230 mAh CR2032 lithium battery has an ultra long three-year lifespan, saving you the annoyance of frequent and. The impressive IP55 dustproof and waterproof rating makes the transmitter tough enough to withstand various outdoor environments. And with a working temperature ranging from -4 F to 140 F, the transmitter can work for you in even the harshest weather conditions. Long Operating Distance The doorbell supports an extensive 1000 ft working range (depending on the operating environment). Rest assured that you'll never miss any important guests or urgent again with the help of this doorbell. Innovative Memory Function One of the great advantages of the AVANTEK Doorbell is its memory function. Every time you turn on the device after a power outage, it remembers your last-set melody and vol level. This makes it not only extremely convenient, but also very user-friendly. Metal will interfere with the signal and shorten the transmission range. Please place the transmitter in areas away from metals.