Replaced my old one, probably 20 years old, and it is still the best quality and the best buy of any a door viewer on the market in my opinion. Solid brass, easy install with a 1" wood bit and has a super clear, wide-angle view. Just a hint. I did not read the instructions and drilled all the way through the door. Messed up a really nice door. Drill half way one way and half way the other. Read instructions and save the grief.
Easy to see through several feet away from the door. Image is large and clear. Although the brass does tarnish with time, it can be polished and doesn't rust away like steel. Unlike the larger door viewers that project an image on a frosted screen, this can be used in low light situations.