WTF was that thing EJ took out of Levin's arm?!! I knew that gal was dirty....

Looked to me like some kind of tracking/storage or info chip.

I was really hoping the P2P killer was going to use that gun on her!

Pity it was Levin that had to die.

It was a microchip.

It was a tracking device.
My dad theorized she was either tracking him because SHES bad, and wanted to follow his movements, or he was the bad guy and she was keeping an eye on him.