A must-have upgrade. The stock drive shaft on my TT-01E made a lot of noise, and is prone to flexing under acceleration. This shaft and cup combo is super light weight, stronger, and thinner than the stock plastic piece. Plus, with the joints included, not only are the weak plastic pieces replaced with stronger ones, but the steel shaft into the gearbox is also replaced with lighter aluminum. Tamiya parts are always high-quality, and fit perfectly. This and a set of ball bearings are the #1 upgrade to any TT-01!