Let me tell you something about it :-
Firefox 4 RC is based on the Gecko 2.0 Web platform.This Firefox 4 RC is considered to be stable and safe to use for daily web browsing, though the features and content may change before the final product release. At this time many Add-ons may not yet have been tested by their authors to ensure that they are compatible with this release.
What’s new in this version :-
- Blacklisted a few invalid HTTPS certificates
- Updated localizations for 29 locales
- Added Vietnamese localization, bringing the total languages available in Firefox 4 to 83
You may use following link to download it :-