Have a look on Wiki:
here.
Note: Problems
On 2 May 2011, the rogue security program MacDefender (also known as Mac Protector, Mac Security, Mac Guard, and Mac Shield) was released. The similarity in name created confusion amongst Mac users, although no affiliation exists between the two. Zeobit has been accused of employing misleading advertising with regards to its promotion of MacKeeper, including aggressive affiliates, pop-under ads and plants sock-puppet reviews as well as websites set up to discredit their competitors. ZeoBit claims that negative attack ads were also launched against MacKeeper by an unnamed competitor.
Do you really need it? I'd be cautious.