Door viewer is one of the types of door hardware. Its function is to observe the situation outside the door through the door viewer indoors, so as to determine whether the door can be opened safely. The RDA-28SS stainless steel cat eye of Lelang Hardware has high-definition lenses, which can see the outside of the door in all directions, the anti-prying thread is not easy to break, and the length can be adjusted by itself, which is convenient for installation, safe, practical and beautiful.