Feature 1. High performance: Smart USB Doorbell has ultra-low power consumption, long service life, and a working temperature range of - 20-70 , which can withstand various adverse weather conditions.2. Modern and Practical Design: Our Wirele Doorbell has a fashionable appearance and practical functions. Lightweight and sensitive, it can be remotely controlled, providing you with quick instructions to ensure that you hear the bell and open the door in a timely manner.3. 30 song Ringtones: SOS Button Doorbell has 30 song ringtones to choose from, and you can choose your favorite music.4. Easy to Install: The Mini Door Bell is easy to install and can be installed in just a few minutes.5. Precautions: In environments with high wirele interference, the transmiion distance of the Wirele Doorbell Receiver may be reduced. If no music sounds, check whether the horn wiring is disconnected. Specification Doorbell receiverProduct name: Wirele doorbell receiverModel: AK-C220616Music quantity: 30 piecesOutput mode; hornDemodulation method: ASKShell material: ABSControl method: equipped with remote controlProduct size: 56.5 * 33 * 5.3mm/2.2*1.2*0.2in(excluding housing)Product weight: 8g (without housing, including speaker)Working voltage: DC5V/1AStandby current: 4.6mAWorking current: 120mAReceiving sensitivity: - 105dBWorking temperature: - 20-70 Single button remote controlProduct Name: Single Button Remote ControlModel: SOS-V2.0Operating frequency: 433.92MHzBattery type: button battery 2016 * 3Modulation mode: ASKEncoding format: EV1527Shell material: ABSProduct size: 45 * 45 * 14mm/1.7*1.7*0.5in (including housing)Net weight of product: 11g (including shell and battery)Working voltage: DC9VQuiescent current: 0.1uAEmiion current: 20mATransmiion power:+10-13dBmWorking temperature: - 20-70