I have used at least a hundred AO sanding belts over the years on my 6X48 belt sander, 36 grit didn't stay sharp long. A while back I got off my wallet and ordered 5 zirconia belts for about $50, 4 times what AO belts cost. Months later I am still on my first zirconia belt, sharp and still cuts like crazy. My belts are German made.
Just a heads up.