Bearings to TT01E are the second must have hop-up just after set of alu driveshaft + cups. Really for those who are not convinced, do not invest into brushless set without buying bearings. Replacing plastic and bronze bushings by bearings will give your car big kick. More smooth driving ( acceleration ), longer time of driving on battery, less wearing of all gears and lower temperature of motor ( less risk to overheat esc and motor). Summarize must have for all TT01E users but please buy it together with chassis becouse changing all items after assembling means that you should reassemble totally your car to replace them.