This is an optional Hobbywing C4 Motor Heatsink and Fan Combo. This aluminum housing heatsink will fit any motor with a diameter of 44mm and will help dissipate heat away from the motor.
Size: 48 x 48 x 16mm
Heat Sink Diameter: 44 x 66mm
This product was added to our catalog on July 29, 2014
The fan is really good and large (40mm)
However the motor heatsink do not fit on Castle 2650KV motor. Also it does not fit well on slash 4x4.
I recommend the fan but not the motor heat sink.
The next issue is fitting it into the EB48.4. It fits but with the Tekno's smaller body would require substantial trimming to be workable. At this point I've determined to find another solution.
Seems like a good product although perhaps best suited for whatever Hobbywing product(s) it's specifically intended for.