Volcus&reg; VC102 Wireless Smart Doorbell: 1 Wireless Button Transmitter & 2 Wireless Plugin Receivers, 52 Selectable Music,4 Levels of Volume Range,Over 500 ft Range,Expendable Up to 50 Receivers (BLK) THE PERFECT SOLUTION FOR ALL YOUR NEEDS - VC102 includes 1 button transmitter & 2 wireless receivers and it can add up to 50 receivers. You can plug the receivers in any room, any location you want to ring when someone press the button transmitter. The easiest flexible bell system for all your needs no matter it is a house, an office, or a warehouse. EASY INSTALLATION & EXPENDABLE- VC102 provides 2 installation options, Double-Sided Tape or Screws/ Anchors, to fit your preference. The button transmitter can be fixed on the wall or the doorframe with screws included, or attached to the wall easily and conveniently by using the double-sided tape provided. VC102 is expendable up to 50 receivers. The receiver can be plugged into electrical outlet in any location you want such as living room, kitchen, bedroom, dining room, or even you can use this set in a warehouse or an office. MODEM, WIRELESS, HIGH-TECH & ECO-FRIENDLY - VC102 wirelss smart doorbell set is an alternative for the old-fashioned doorbell. No need to hide wires and easy to install and easy to use. The modem design easily blends with the decor of your home or office and you can match different color receivers according to your needs. Features low power consumption technology (&lt;10mVV) LONG WIRELESS RANGE, LED FLASHING INDICATOR, SPLASH PROOF (IP44) - Features an industry leading wireless working range of 900 ft in the open area. Remote wireless signal passes through walls easily and reach up to 500 ft with metal security doors and walls. Features LED flashing indicator on the receiver and rated IP44 splash proof button transmitter. 52 SELECTABLE MUSIC & 4 LEVEL OF VOLUME RANGE - Features 52 music for your selection and 4 different levels of volume range for your needs (25dB to 110dB)