This is a optional G-Force Static Wick. The G-Force Static Wick is designed for RC helicopters to control the static generated by a belt driven tail system and the rotation of the tail blades. Static is more prevalent in dry weather or winter conditions. If you are using a FM system, you could potentially deal with constant glitches caused by static, but if you use a 2.4GHz system, a lockout could result from enough static interference which could cause a catastrophic failure.
The G-Force Static Wick works on all electric helicopters and is designed like the full size system to discharge static quickly, reducing static interference.