Grasshopper 18 inch heavy duty (1/4 inch thick) blade is used on 52 inch mower decks. It is also used as the outer blades of the 48 inch cut deck. (Use one 320233 for the center blade on that deck.)
Contour blades are good for all-around use. Provide a clean cut in most condtions. Also recommended for bagging. High lift blades are recommended for lush, high volume conditions.