What's the difference between SLR and double reflex?

Double-sided mirror is also called double-sided mirror and single-sided perspective glass. What is its principle? Ordinary glass is made of chromium, aluminum or iridium film by vacuum coating. This glass can reflect most of the projected light back.

It is an ideal choice for surveillance, security and monitoring, but it is often used for voyeurism. ? In a well-lit room, one side of a single-sided mirror looks like a mirror, but from the other side, it is an ordinary stained glass window.

When going to the toilet in hotels, hotels, gyms and other places, keep your fingernails in front of the mirror. If there is a distance between the image in the mirror and the nail, then the mirror is a one-sided mirror. If there is no distance between the image and the nail, it means that it is a double mirror, which means that you are likely to be exposed to others' sight.