Noticed my local LOWES had 3 in stock so I stopped by to check them out and see if they are the same as a Greenworks 21" blade.
YES … Kobalt blade number 648547 has the two "ARROW" cutouts and were even stamped with 333041179 which is the correct Greenworks blade that fits all G-Max 40V, 60V & 80V mowers.
Sales tax by me is 5% and using my Lowes card I get 5% back so if I were to order 2 blades from Greenworks it would be a wash with shipping & no tax … I'd have to buy 3 blades to be cheaper than going to Lowes.