The de_arena12.zip file you have requested: Maps Levels Missions / DE Maps / A to B Titles / Arena12 Map - 2.24mb is not available. Perhaps try browsing all files for the game Counter-Strike: Source and upload any files you want to share or are missing. This is the only information we could locate:
It's my first CounterStrike-Source Map, i hope you enjoy this little Map.Defuse/Bomb Map for 2-12 Players. This is a Counter-Strike: Source map entitled DM_Arena12, it handles up to 12 players and is a Defuse Map.