Feature: 1. USB Wireless Doorbell: Digital wireless DC doorbell, wiring free, plug and play, long distance reception. It has good performance. 2. 3 Adjustable Volume: Regardless of the balcony, kitchen, horizontal can hear, convenient for family use; 3 adjustable volume, the sound size as you wish. 3. 38 Ringtones Freely Switch: This doorbell comes with 38 ringtones to choose different exclusive ringtones for different neighbors, perfect for home use and as a pager for the elderly. 4. Multi Functional: Not only a doorbell, but also a pager, when the elderly, babies, pregnant women sleeping alone need, a press will know. Plug in the rechargeable battery, can be moved at any time. 5. Strong Signal Long Distance Reception: Can penetrate 3‑4 walls, open distance range up to 150 meters, in open areas, ideal for large houses, including villas, apartments, offices, stores, warehouses, etc. Specification: Item Type: Wireless Doorbell Weight: 77g / 2.72oz Commodity Material: ABS Emitter Operating Voltage: 5V (USB power supply) Power Consumption: <0.25W Operating Frequency: 433.92 MHz Operating Temperature: -10°C~+45°C Controllable Volume: ≥50dB/1m Remote Control Distance: >150m (open space without obstacles) Transmitter Battery Type: CR2032, 1 x button cell Battery Capacity: 160mAh (shipped with built in battery)Transmit Power Consumption: <10mW . Package List: 1 x Transmitter1 x Receiver1 x Double Sided Adhesive1 x Instruction Manual