I wanted to remotely mount my PSU for my Ender3 and all of the other mounts had them orientated flat against the bottom of the tables and I didn't want to hinder the airflow. There is enough room for the wires to come out of the bottom as well as you can see in the pictures.
When installing this, there are countersunk 4x8mm screws in both the top and leg section. Install the brackets to the PSU before mounting. I used 5x20mm screws for mounting to the enclosure.