When more than one grit is necessary to resharpen a cutting edge, a craftsman will often use a combination bench stone to lessen both the expense and inconvenience of using two single grit stones. PTA 120/320 grit combination bench stones are made of aluminum oxide with 120 coarse grit on one face for repairing steel cutting edges and 320 fine grit on the other face for sharpening and maintaining them. These stones are impregnated with oil, eliminating the need to presoak them prior to use.