When you keep your lawn mower blades sharp, your grass will see the benefits. Maintaining your blades will result in a cleaner cut and ensure your grass is greener and more healthy-looking. This Arnold 21 in. Universal 3-in-1 Lawn Mower Blade is compatible with most makes and models, so you can find the push mower parts and riding mower parts for your machine.For detailed installation instructions, please refer to your operator's manual.