I've used it several times and it has worked without any issues. I needed to contact the seller for activation related support which was not unexpected. I made sure to send them an email during their business hours and they replied with 30-45 minutes and shortly thereafter they had everything setup including the wifi profile.
So far I'm very happy with my purchase, It was indispensable in troubleshooting issues on my ML500.
Replied by Joyce on Apr 3, 2020
Thank you for your support and feedback on our website.
Any further questions please feel free to contact us.