Dear holders invest in a little more Euros. The big problem in these brackets is clearly the material used (hard plastic) and the resulting "Durchgehänge" of boxing. I have hung small Onkyo satellite speakers with it. The weigh wenns comes up 2 kilos. However, this is already exposed to the initial stage of overload the mounts. More weight is as well not even if an attractive appearance is to be maintained.
By the by - 3 Sternle because your purpose though but do not meet the holding what was promised.