Firefox ESR

Mozilla offers an Extended Support Release (ESR) based on an official release of Firefox for desktop for use by organizations including schools, universities, businesses and others who need extended support for mass deployments―

• https://www.mozilla.org/en-US/firefox/organizations/faq/
• https://wiki.mozilla.org/Enterprise/Firefox/ExtendedSupport:Proposal
• Downloads, http://ftp.mozilla.org/pub/mozilla.org/firefox/releases/latest-esr/
• Wikipedia, http://en.wikipedia.org/wiki/History_of_Firefox#Extended_Support_Release