World Champion ACER Racing 6x12x4mm Ceramic Ball Bearings.  This is a 6x12mm ceramic ball bearing also known as a size MR126 ball bearing, Traxxas 5117 ball bearing. Diamond polished Silicon Nitride (Si3N4) Balls, HSR cage technology and sealed on both sides.  Lubricated with lightweight and 100% synthetic ACER Racing SIN Oil instead of thick grease for super fast and super smooth action.

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