1ABS back cover effectively protects the camera against water, rain, dust. Surface finished with matte process, perfect in texture and quality. 2Simply press the button on outdoor camera unit, and visitors can make a 2-way communication with host after the phone is answered. Easy and convenient. 3Equipped with 4 infrared LED lights for better night vision. Normally work even in the dark night. Adopt professional HD CMOS sensor, you can see the visitors' faces clearly. 4Support unlock the door, monitor and no disturb function. Easy to install and operate. There are 25 beautiful chord music ringtone can be chosen. The volume is adjustable. 5When someone press the call button, you can directly pick up the handle of the telephone to answer or press the hands-free key to talk.