On this door viewer, the plate rotates freely and has a quality feel; this privacy cover is perfect for preventing those with reverse peepholes from spying on you. Perhaps you initially thought about buying the cheaper, smaller version, but you will be glad to spend extra on this one. Perfect peephole for homes, offices, hotels, and front doors where you need to see, monitor, spy, and peek at who is outside your door when the doorbell rings before you open, providing you with extra privacy and security. A must-have addition to any intercom system, security door monitors, or door accessories. Its material is solid brass, a high-quality door viewer, and it has a nice 220-degree viewing angle. After installation, you can see a person standing outside from the top of their head to their feet, and you can easily see the entire surrounding area. It offers top-quality security for you and your family. The required hole in your door is 1.1\" / 28 mm, which is quite large. But the advantage is that it is very good at gathering and transmitting light. It is very clear through the glass optics (unlike cheap peepholes with plastic lenses). The lens is 0.675\" (17 mm) in diameter. Because the lenses are large, the image is displayed clearly and distinctly. This is suitable for 1.65\" to 2.16\" (42 mm - 55 mm) thick doors. Insert the door viewer into the hole, then screw the two sides together and tighten by hand. The viewing tube is slightly larger than many other standard peepholes, providing a better field of view. You can apply a thin layer of silicone sealant to the inside and outside of the flanges before installing the unit to keep moisture out.