Serpent have introduced new gears diff for the Eryx 411. The gears diff has been improved with new shaped composite gears to make the whole differential feel smoother. The changes to the tooth profile are only small, but make a big difference as you will notice instantly. There are the same standard gears diff in the Project 4X and the new gears were in the kit since the start. Current Eryx 411 drivers only need to update the new internal gears as the case remained the same, but the performance will be even better if all is new.