@Tubs 

Good day.

Thank you for your time and patience.

TL-WPA4220-KIT (AV500) could work with the AV600 extender.

And all our power-line adapters are compatible with each other.

For more details about how can I select the power-line device:

https://www.tp-link.com/support/faq/2725/

Thank you very much.