This is a 30ml tube of Team Losi Racing silicone differential oil. This differential oil is used for 1/8th scale off road buggies, truggies (and some 1/10th scale on-road touring cars). 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 oil in your differentials is one of the most important tuning options for off-road buggies.