Made of resin lens and zinc alloy, ensuring and durability- Optical lens with 200-degree visual angel gives a crystal clear view with an extraordinary wide angle coverage.- Privacy cover design can prevent outside people peeping through the viewer, giving you the hightest level of pricacy of your protection and safety.- Pipe diameter is adjuastable and peephole is easy to install.- Suitable for anydoor within 35-60mm/1.38-2.36 Inch thick.