The benches are unfinished. They are evenly worked over with a 6" disc grinder with 30 grit paper.
If you have never tried a disc grinder as a wood remover, I highly recommend that you try it.
You will never go back to a belt sander again.
It works great!
If you want finer sanding, I would go from there to 60 or 80 grit, then move to 100 grit in a palm sander.
A 6" disc sander with 30 grit paper eats wood as fast as a hand held power planer. Pulling back on it works best. Pushing on it can cause serious mistakes.
Zulu