This seems to be a well-made product. This review might help you to fit it properly. At first I could not see how to fit this to my handlebars and get a good view, because when it arrived the mirror was in line with the bracket and not at right-angles to it as shown in the photo, and I could not work out how to adjust it.
In the end I realised that the stem, stiff though it is, not only bends but also twists. You can bend it - and also twist it - to any angle you like! There is no need to unscrew the little flush black cross-head screws at each end of the stem (which I did - to no benefit, nothing can be adjusted).
So, just use the supplied tool to unscrew/screw in the long silver bolts and attach to handlebars, then carefully bend/twist the stem - it really will go where you want it to, and stay there.
I have knocked off one star for lack of instructions, but I like the product.