Product Review (submitted on September 21, 2020):
I actually bought this to upgrade my 12S to access. The upgrade was very easy. The module plugs into the connector as the original board. The 12S has one external and one internal antenna. The module requires 3 antennas. I removed the antenna from the BT module and used it as the third antenna on the module. I used an old receiver antenna as a replacement for the BT antenna. I upgraded the firmware to the 10S upgrade download on the Frsky site. If you are running OpenTX, you will need to check the box ‘internalaccess’ and update the OpenTX to 2.3.9. The upgraded 12S now works with both Access and Accst receivers.