This adapter fits two 2.5inch SSDs or HDDs in one 3.5inch slot.
There are 2 variants, one with additional intakes for two 40mm fans and one without.
I think for a better air flow, some kind of rectangular exhaust makes sense if you're going to use the fan variant.
For mounting in a 3.5inch slot you need 6 or at least 4 heat inserts (M3x5 with a diameter of 4.1mm).
If your slot has only bottom holes for mounting, you can just use M3 screws or 3.5mm wood screws or similiar.
The author marked this model as their own original creation.