I picked this bad boy up, and it's definitely legit. The cable length is 10 feet, all the action is smooth and solid. I also picked up one of the USB offerings, and it too works great.
This is available via Amazon, and I recommend it to anyone who attends local tournaments. If you play Genesis games online or via emulator, I recommend the usb variant.
https://www.amazon.com/Retro-Bit-Official-Genesis-Controller-6-Button-Arcade/dp/B07P255V8J/ref=sr_1_4?keywords=6%2Bbutton%2Bgenesis%2Bcontroller&qid=1573569925&sr=8-4&th=1
This is not an affiliate link or a sponsored promotion. I just figured if everyone in the community had one, they wouldn't have to worry about what controller they end up with when they attend tournaments, as there are a ton of different options out there.