Befaco Knurlies don't really fit in the topmost screw rail.
Some modules can't be installed into the 45º (upper) row, e.g. if they have knobs too far up on the panel, or the knobs are sticking too far out, i.e. they prevent the cover to be replaced onto the case.
Otherwise, as a base case it fits its purpose perfectly. Top row can even handle modules up to 12cm deep.
I modded mine to fit in 4 spring tanks (Belton/Accutronics, the ones from Thonk), as some busboard screw holes are arranged so that these tanks can be easily fixed in two places.