Wire-free Smart Doorbell Camera with Cordless ChimeTECGUUD front door camera is powered by built in 5000mAh rechargeable Lithium battery, no more annoying with wires/cables problem, the included door bell ringer powered by 3 AA batteries and carry 4 ringtones, pick up the one you like as a reminder, never miss any visitor calls when the phone is muted or not around Easy Installation with Tamper Alarm TriggerThere is a tamper alarm button behind the security doorbell, it will be pressed when you install the video doorbell correctly, the button will bounce back and an alarm will sound if someone intend to separates the doorbell from the shell, feels much more secure with the key feature Pre-recorded Voice Message with 2-way AudioTECGUUD doorbell camera system equipped with advanced high db microphone & speaker, which supports the real-time speaking directly to anyone who approaches your front door without having to get up and answer the door, you can leave 3 10 seconds voice mes