The door-viewer that is easy to install, well-made, and it provides a clear wide-angle view. The interior viewing hole is a good size to look out of, and the fancy little rotating cover offers peace of mind that no one can in. Features -Material: Zinc alloy. -Size: About 7.00X5.50X5.50cm/2.75X2.16X2.16in. - Battery: 2 x AAA batteries(Not included). - After installing it, you could see a lot of the area. It offers the security for you and your family. - It is a modern security door viewer and peep hole for doors. - Fine workmanship and creative appearance ensure its popularity and practicality. - Perfect peephole for home, office, hotel and front door, etc. - Where you need to see, monitor, and peeking who is outside your door when the doorbell rings before opening, providing you extra privacy and safety. -Instructions for use: 1. Open to the left or right. 2. Use your finger to lightly press the battery cell position, pull out the inner core after the inner core is separated, and press in 2 AAA batteries on the inner core. 3. Put the inner core back in its original position, and press it in with your hand to make it jam. Note: This inner core is a cycle . Click to release, and to jam. Package list: 1 Viewer