Designed for #6x1/4" Wood screws. I believe the actual mount for the 2.5" membrane canister uses #8 screws, around 4mm. Slots in the bottom for 10mm (0.4") bumpers
If yours didn't come with those mounting clips, I'm designing some right now.
I designed it for this guy: https://a.co/d/bPjQX4z
The author marked this model as their own original creation.