The standard mount options of the Core 200 reservoir might not be the greatest - not because of what alphacool provides but what your case dimensions are. In this specific case, the beQuiet Light Base 900 FX, there's just not enough room for the reservoir to be mounted the intended way.
This new bracket will let you mount it as Alphacool originally intended but with enough space to the bottom to fit in this case but also enough free space left to put in an additional radiator with 30mm height into the bottom.
It screws to one 140mm Fan and has an additional pair of holes for when there's an additional fan on top. This ensures a secure fit.
The author marked this model as their own original creation.