Major versions of Joomla are seperated into different series. (RE: 1.5 series, 2.5 series, 3.5 series, etc). We have different versions of our software for each specific series that Joomla.org currently supports. At any given time this could be 2 different series. So to offer the best integrations we have found it better to offer version specific extensions. Your purchase must be made for the exact version of Joomla that you are currently using. If at a later time you wish to migrate to a later version of Joomla please contact us and we can offer you an upgrade discount to the newer versions of our software.