1?��Applicable door thickness is 55-90mm, suitable for wood, fiberglass or metal door. Easy to install, the door viewer can be replaced within 5 minutes without tools. 2?��Precise thread casting, easy to install, the length can be adjusted properly, anti twisting, anti-skid and anti-pry, protect your home from burglary and home invasion. 3?��The 220-degree viewing angle provides security for identifying visitors from behind the locked door, and you can easily view the entire surrounding area of people standing outside. 4?��The inner wall is finely butted with thread, safe and without danger, which can effectively prevent thieves from prying and destroying door viewer with tools, more convenient to use. 5?��A sturdy and heavy duty viewer cover increases your safety. After cover the cover, visitors outside cannot see through the viewer into your home, providing protection for your safety.