This is a very good ball bearing set. It reduces the friction a lot, so you go faster, you have more driving time, motor, ESC and battery are less hot, the steering is more precise and there is less erosion. It also looks good and it is pretty handy that it is pre-lubricated. Another thing is that they are very strong, you will not break or crack them easy. It is not essential to buy it in use with the standard motor (although it is better), but with a faster motor you have to buy this ball bearing set. If you have a TT-01E do not buy the ball bearing set for the TT-01, because that is an incomplete set (for TT-01E). It is well worth the money, so I will not hesitate buying this product.