This is a 2oz bottle of a bottle of Team Associated Silicone Differential Fluid. Made in the USA exclusively for Team Associated by Lucas Oil Products. The thicker the oil, the less your differential will "diff out" in the corners, where the two tires will turn at different speeds. Changing the differential oil in your diffs is one of the most important tuning options for off-road vehicles. Choose from a variety of weights from the pull down menu.