For use must be glued metal discs on your device (surveillance cameras in my case).
The double-sided does not take glued if your device heats a little.
Quality is average: the telephoto lens is the best (I replaced a Cokin lens, sharpness and transmissibility are much better) for wide angle, sharpness is right in the center, the image loses sharpness at the edges while the quality of the fisheye is very average and the edges are significantly blurred.
In case of strong light, you'll see it appear chromatic fringes.
Attention must really think your goal is to small diameter (6mm otherwise the image will be hidden on the edges), and its lens is not inserted into the phone (must be flush), otherwise the image is blurred
Used with a phone with a quality camera, you may be disappointed.
I use it with cameras that have VGA resolution (low), so the result is satisfactory.
I have other lenses of this type (and Cokin XcSource with mounting clamp, all more expensive), they are of lower quality, is why I put 4 stars, especially for less 10.
