The sv_downsized.zip file you have requested: Maps Levels Missions / Survival Maps / L4D Downsize Survival Map - 9.99mb is not available. Perhaps try browsing all files for the game Left 4 Dead and upload any files you want to share or are missing. This is the only information we could locate:
Downsize in Left 4 Dead has a whole new definition with zombies waiting to punch out your time card, permamently. They are actively hiring meat shields and sitting ducks at this office.