I used commercial grade fabric. But if I did it again, I would probably use two layers. I backfilled and packed the dirt behind the rocks as I built the wall and there is a lot of stress on that fabric in the voids between the rocks in spots. I used 50" X 50' of fabric for about a 30" high wall. I should have went with wider fabric, too. By the time you lay the fabric down under the first layer of rocks and the fabric filling in all the voids, the 50" gets eaten up pretty quick. I fitted smaller rocks into the voids on the dirt side of the wall as best I could, but still should have went with wider stuff.