Well got to try the new blades. They are working great. I wouldn't worry about that small size difference. My Review: If you are looking to replace your "wore out" factory blades, then these are the way to go. Should you run down and purchase these and replace the original? No. They cut the same (not better or worse) as the OEM blades. They are really heavy and should last longer than the OEM blades, but I can't prove that at this point. They will be great for mulching leaves, but it will be a couple of months before they start to fall. I also installed my hydro filter guard. It should help with brush when the MMM is off.