Firmware for download, Which version?

I have a MT300N-V2. Under the firmware directory, there are V1, tor, testing, clean. May I know the definition of each directory?
If I flash with he testing firmware (eg. V3) , can I revert back to older firmware later?
Thank you in advance.

This text is used to describe echo model folder.

In each model folder there maybe several sub-folders:

“v1”/“release”: v1 or release folder contains the main official firmware for that model.

“testing”: testing folder contains the latest developing firmware, it is pre-release stage. The firmware usually have some bugs.

“clean”: clean folder contains a clean firmware with minimal packages, with LuCI installed, wifi is disabled by default. It is the same as OpenWRT official firmware, which doesn’t include any GL.iNet packages.

“tor”: tor folder contains a tor firmware for that model. We don’t maintain Tor firmware any more. If someone wants to use Tor VPN, please refer to the guide. Tor - GL.iNet Docs

“nand”: Only AR300M series contains this folder. It might contains above folder for NAND.

For your question: Yes you can revert to old firmware. Do NOT reserve setting if you change from different versions.