These Spare Part wheels for the DB01 Durga are the same as those used for the race-spec TRF501X. Therefore they use a different type of hex hub attachment than previous chassis like the DF-03. This hex hub provides a close fit for precise wheel attachment, ensuring reliable off-road performance.
In cases where the hub and wheel fit is tight, take greater care when aligning the hex hub with the hex-shaped recess of the wheel and secure using lock nut.
Source : Tamiya