This is a brand new, re-engineered replacement high performance CDI unit (Rev Box) for your 2008-2009 Arctic Cat 500 FIS 4X4 Manual or Automatic. This redesigned unit boosts RPM levels by 1000 and the timing curves increase horsepower by 5. This replacement part features a higher rev limit and removed reverse rev limit. It overrides for full performance at all times. This unit features increased spark energy, improved throttle response, easier starting and a plug-in module replacement that allows for easy mounting. This CDI unit meets or exceeds all factory specifications and is a breeze to install. This unit replaces Arctic Cat # 3530-039 only. If you have 3402-683 then we are able to repair it for $185. If your unit is beyond repair then there is no charge.