Alc 40125 20/40 grit corn cob – 50 lbs. 50lbs, 20/40 grit, 0.053″, 4.5 mohs; slightly harder than walnut shells; can be used in many applications of surface cleaning, removing graffiti, including log homes and removing smoke damage on wood surfaces; note: the size of the blaster nozzle should be three to four times larger than the grit size of the abrasive being uses, the larger the nozzle the more cfm of air is required