This is the HobbyZone Sonic Combat Module: ABS, FC2, P-51D, FBF, FW, F-27/B

Overview:
Plug in the Sonic Combat Module and take on similarly equipped HobbyZone planes in aerial combat. When “hit”, the SCM temporarily disables your opponent’s motor for ten seconds while still allowing them to steer.

The Sonic Combat Module is compatible with any X-Port equipped HobbyZone airplane, like the Firebird Commander, Aerobird Challenger, and Aerobird Xtreme.

The Sonic Combat Module also works with X-Port equipped ParkZone Aircraft such as the F-27 Stryker, and Slo-V.