5 Lbs. of 400 grit aluminum oxide. This abrasive is used in the Paasche Airbrush AEC, AEC-K, AECR & ER-1S etching tools. Can be used for etching hard surfaces like glass or metal or for lighter work like paint or rust removal. The 400 grit will give a finner finish then the 240 grit but not cut quite as fast.