Scan Bolt

The scan bolt is an unlockable ammo type for the XBOW.

Battlefield 3
"Scan bolt fires a sonic sound on impact spotting enemies within a 10 meter radius."

- Battlelog description

The Scan Bolt is tipped with a radio emitter that scans for enemies in a 10m radius. Scanned enemies are automatically spotted with a special flashing icon. The radio head inflicts minimal damage, least among the bolt types. Infantry that have been spotted by the bolt can hear a distinctive trill upon its impact. The Scan Bolt is unlocked after completing the assignment It Is Ok To Thank Me.