I don't really understand how to adjust and work it properly yet so I have delayed my review a few days. Taking it out on a nice sunny day it appears to be a nice compact monocular optic. It appears to have a magnification of about x10 but I can't seem to get the higher magnification from it. Various bits twist but it is unclear how to achieve 300x zoom, but with such a small objective lens it would expect the view to be terrible based on the small 40mm aperture of the optics. Just using it as a x10 optic it works just fine. My phone is big so it needs a lot of fiddling to get it adjusted to take pictures and view through the camera. Most of the images you will be taking with this is a big black square with a circle in the centre of the view of what ever you are taking a picture of. Not ideal but even at x10 it is x10 optical zoom which is always better than digital zoom.

Everything went well. Thanks Banggood.