Adopting great quality material, which lets you use it for a very long time. Though it is simple , it's so practical when you use it. The excellent workmanship of our product will bring you a good experience. Easy and convenient to install and use, it is a very useful door viewer. Features -Material: Zinc alloy. -Size: About 7.00X5.50X5.50cm/2.75X2.16X2.16in. - Battery: 2 x AAA batteries(Not included). - You can easily identify who is before you . - A must safety complement for home, office, hotel and anywhere you need to view who is outside your door before opening. - It has a simple design, but very practical in use, giving you a . - It is easy to use and install, bringing of convenience to you. - Made of high-quality material, which is durable and lasting for use. -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