I bent the original blade when it hit a raised water meter cover. I thought I had ruined the mower but figured for the price of a new blade I could be wrong. I was, it was the blade being out of balance causing the mower to shut down after it got up to max speed. Fitted the new blade, you cannot get that wrong, and the mower worked fine. Very pleased, love my Greenworks 21" mower.
I have not installed it yet, but it looks like the right blade for my Kobalt 21" 80V mower. The stores have not had it stock so I bought this one online when I found out that the Greenworks blade is the same as the Kobalt blade.