Why won 4-star!
The magnifying glass is for the unbeatable price of only 63, - convinced extremely solid and the magnetic mechanism for attachment to the tripod plate (very convenient).
I think for under 100, - there is no better product and I have already tried a few / am in possession of those.
eg on a Sony a7 - gorgeous! Solider maintenance, compensation for glasses (also not to offer), practical folding mechanism.
Too bad wait, that she was not the hoped solution for BMPCC only. I would recommend this product but still highly recommend.