I got the 40v kobalt mower on clearance, it was an open box display, and it didn’t have the safety key. Didn’t know it was suppose to since my other mower didn’t need one. I searched and couldn’t find a key so I called kobalt. They’re sending me one for free. I got the price and part number just incase I ever need to get another one. It’s part # 53393-311051479, & they’re $10. Looks like that part number pulls up a safety key for Greenworks that may work, it’s $15. But can just call 1-800-3kobalt & order one from them like I did. Hope this helps someone.