Download the new RouterOS 6.13 release over the torrent network: http://www.mikrotik.com/download/routeros-ALL-6.13.torrent
Otherwise please visit http://www.mikrotik.com/download to pick exact version!

6.13 changelog:

*) console - comments are now accepted where new command can start, that is, where '/' or ':' characters can be used to start new command, e.g. /interface { # comment until the end of the line print }
*) backup - backups by default are encrypted now (with user password). To use backup on older versions, you should disable encryption with dont-encrypt flag when creating it;
*) files with '.sensitive.' in the filename require 'sensitive' permission to manipulate;
*) lcd - reduce CPU usage when displaying static screens;
*) l2tp - fixed occasional server lockup;
*) pptp - fixed memory leak;
*) sstp - fixed crashes;