I have a Kobalt 21" walk behind mower. What compatible blade could I get from Amazon that would fit this mower? Preferably a High Lift or Regular blade, and not a Mulching blade given my mowing schedule. Lowes offers a 'Kobalt 21-in Deck Multipurpose Mower Blade for Walk-behind mowers' that I assume is the "official" replacement, but for various reasons, I'd like some other options available via Amazon.