The Arnold 42 in. Mulching Lawn Mower Blade Set helps care for your lawn. When you mulch your lawn, the clippings are cut into very fine pieces that are returned to the grass. This helps to keep your lawn healthier, as it returns nutrients to the soil. And you won't have to spend your time raking or bagging the clippings. These replacement blades are compatible with tractors with 42 in. decks.For detailed installation instructions, please refer to your operator's manual.