It appears to be a brand. Sold on Amazon. Advertizing says, "Suitable for Festool ETS and RO sanders." https://www.amazon.com/s?k=serious+grit+sandpaper&gclid=EAIaIQobChMIjoXg1-_k7gIVCvSzCh3vNA51EAAYAiAAEgL5c_D_BwE&hvadid=433824713974&hvdev=c&hvlocphy=9004249&hvnetw=g&hvqmt=e&hvrand=16608429821987973014&hvtargid=kwd-914644240937&hydadcr=28596_10166501&tag=googhydr-20&ref=pd_sl_6xn1cwomcu_e
I too thought the post was about really low grit. Every time I see these sander reviews that can really go at it with 40 grit or less and mechanically how they can really take off surface, a smart aleck comment comes to mind thus: In the olden days woodworkers used a hand plane before sanding, every hear of it?
Seriously, does anyone even think of the hand plane option rather than sand/grind away at the poor defenseless work piece?
You’re absolutely correct Clark...to remove a .005” thick swath of wood, 5” wide would take 2-3 swipes with a hand plane and take 4-5 seconds while sanding away that amount of wood will take at least a minute...that’s a 12x-15x multiplier.
I've never heard of it?
I've been using Granat and Klingspor for a long time with good results. We have also experimented with a couple of different ones from Wurth. The Purple is not so good, the green is ok.
In the finer grits, especially on solid surface material, we also use Mirka Abranet or the foam backed stuff from Klingspor.