Walnut Shell media. $25 for 50 lbs. Factory 50 lb. bag of fine grit. Quality clean commercial/industrial grade walnut shell. This is not "B" grade that sells for animal litter. And...it doesn't go bad. If you rotate it as much as you should, it will go faster than you think. Corn Cob media. $30 for 40 lbs. For the beautiful final polish and / or case lube removal. Factory 40 lb. bag.