The blades on most lawn mowers are held on with a 1/2" or 5/8" bolt and no place for the blade to give. That is why you get nicks like the tip of your little finger. The Meg-Mo Knives are held on with a 10mm bolt (7/16") and the knife weight is 6 oz. and can give so therefore we will only get nicks like the tip of a pen. Being free swinging, we can make the knives of better steel and rock-weld harder. This is why the Meg-Mo Blade lasts longer, which makes them less expensive than the OEM blade. Knives are all that you need to buy from then on. They are $4.95 each. The Meg-Mo Blades are centrifugally balanced so they remain balanced at all times when running.